DeVere 504 Help - Wonky head

I have a DeVere 504 Dichromat that I've had for several years. I gutted the head and use it with a cold light that I've dropped in. Not the ideal solution... but it works. I'm extremely pleased with the results I've been getting with it, given the situation. Namely - it's rock solid and I get incredible stability and repeatability and ultra sharp grain all the way across even large murals... HOWEVER

Whenever I remove the negative carrier, the light housing above slides out a little with the carrier. It appears that the housing is only sitting on two pegs attached to the carriage assembly behind. It strikes me as a 'not-very-optimal' state of affairs and I'm wondering if anyone else has had this 'issue' and/or if there's any way I can possibly tighten the whole thing up somehow or 'lock' the lamp house into place. It kind of freaks me out a little.

Here's the enlarger:
http://www.c4gallery.com/workshops/photo/darkroom.jpg

Two other questions for the right person:
anybody know of a good cold light unit that's square I can use instead of my round aristo which occasionally vignettes a little bit?

Any good leads on a new negative carrier - the old one is pretty beat up and needs to be covered in tape to stay together...

thanks

I have a 504 with the same head and I am not sure how the light housing can slide out. My only thought is that the retaining sprung clip at the rear is not attached to the screw head on the back of the head. This 'clamps' the head down onto the 2 rising pillars. I attach a photo to show what the rear should look like.
Hope this helps, Mark Walker.

Yes - I have the EXACT model and same set up as that Mark... thanks for the response. It looks IDENTICAL incl. spring, fasteners etc.. except the head freely slides out along the two horizontal bolts (that have the nuts on the outside) - maybe I'm missing an internal nut? But I don't see where they come through inside the lamp housing... weird... maybe I should look more closely - but I hate going in there as getting the cold light repositioned can be a bear. I mean - it all WORKS - but it's just disconcerting sometimes to be pulling the carrier out and the head comes out about an inch or so... makes me worry about the cold light alignment...

Here's another attached picture that shows a revolving retainer on the horizontal bolt that corresponds to the bottom of the 'L' shaped slot in the head. The head slips over this and then drops slightly so the retainer is within the vertical slot of the 'L'. It is this that prevents the head sliding forwards and it sounds like yours are missing. If this is so, I suggest removing the bolts and take them to an engineer who could tap in something suitable to the existing holes in the ends. Also, check that the cam operated by the lever for lifting the head is giving sufficient clearance for sliding out the neg. stage: the clearance is only @ 1/8th inch. Hope this is clear enough.
Regards, Mark.

Hey thanks again, mark! Yes - I'm SURE the cam is messed up - because A) the head lift is insignificant (too much friction when pulling out and B) poor pressure when lowered (leaks a LOT of light through the slot - so maybe I should really look at that assembly then... I wonder if there's a service manual anywhere...

What's the general procedure for removing the lamphouse? just detaching the spring and lifting out?? I thought that might be a good way to inspect things (??)

Before you take off the lamphouse it is VITAL that you lock the head rising mechanism with the knob at rear of board. The stages are under tension and are counterbalanced by the weight of the head.

That was just a quick warning ! Once secured, yes, you detach the sprung clip holding the head (which is heavy, so make yourself in a good position) and lift slightly and gently rock the head off the horizontal bolt arms. Then you will see if the retaining pieces on the arms are present. Also, lift the 2 rising posts that work off the lifting cam and check that they slide up and down smoothly, they can get messed up with old lubricant and lint. I had to replace one of these as someone had fitted a replacement that was too short.
Basically, the Deveres are a pretty bomb proof design (they were widely used in the British military afterall) that are easily adjusted with a spanner (US wrench ?), a screwdriver and a 1/16th Allen key (if I remember right). Give it a good look to see which screw and key affects which plane of movement as all the planes are adjustable. If you are satisfied that your prints are squared and sharp across the base board, then don't adjust anything. If not then it is worth spending an hour with a level and the 3 tools needed to level everything starting from the foot bolts up.
If the head is too tight on the neg. holder it could be that it is leaning forwards. The tilt of the lamphouse is governed by 2 nylon set screws on the rear vertical plate that make a friction surface to the rear lamphouse'. Also, the head stage could need levelling which is done with an Allen key and screw driver on the fixings on the rear vertical plate. You alternately loosen and tighten with the Allen key and driver until the stage is level, but just a half turn makes a big difference to the level. It sounds complicated but if you work through logically all the necessary adjustments should be possible.
I have to sign off now because I am up ridiculously late (1:40a.m. here), but post some pictures if you have any doubts or problems, happy to try and help. Regards, Mark.

Mark- thanks for the info - been awhile - but I FINALLY got around to this..!! Got the head removed and the left 'retainer' (with the little wheel thing on the end -no idea why it needs to be a wheel!) is rotated around in the wrong orientation. Mine's pointing UP - so I guess that's why it was sliding out... just have to loosen, rotate back and then re tighten and I guess we're good to go... thanks

Good to here that you have pursued this and that the fix was straight forward - the wheel is there because the head slides against it when it is raised and lowered (to use the negative stage), so it is a better engineered solution than a plain friction surface. Any more issues and you know where to come,
Regards, Mark Walker.