I agree with Anscojohn on most points (and thank him for the typing). Here are a few comments:
Secondly, I'm pretty sure it's never been moved until I picked it up (carefully too), should I worry about alignment on this?
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Probably just need to check that the back girder is attached properly to the baseboard.
Thirdly, it came setup for 35mm, with a lens and carrier. I have what looks like a small house shaped unit that they said was for it, but I'm not sure what for. Does anyone know? Is this needed for enlarging 6x6?
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Sounds like the "house" is a mixing chamber, as shown on this exploded diagram from the Beseler site:
http://www.beselerphoto.com/img/exploded.dichro67.body.gif
You can use the 6x7 mixing chamber for that size and smaller. The only reason to use the 35mm chamber is to get shorter exposures for that format.
leave the color knobs zeroed out for B&W
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for graded paper, switch the white light lever to white light. If you need less light, you can set each of the knobs to the same filtration, and by doing so you will reduce the intensity.
or can they act as variable contrast filtering for VC paper?
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this is how I use my dichro head. There are charts available (check the websites of the paper manufacturers) which indicate approximate equivalents between contrast filters and dichro head settings, or you can consider using split contrast filtering.
And finally, does anyone know a (relatively) cheap place to get 6x6 negative and slide carriers for this?
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I've got all mine through eBay - although I am not aware of a carrier for mounted 6x6 slides.
You will most likely need a lens as well for 6x6, and I would recommend looking for a lensboard as well, also from eBay.
Are the 67s carriers that same as the Printmaker 35 carriers?
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Yes
I've been using my 67C since the 1970s, and have had a dichro head for about 5 years.
One further comment - some of the dichro heads require a separate power supply, while others have the power supply built into the head.
If the head doesn't have a separate power supply with it, but appears to have a regular plug, try it out, because it probably is fine.
Here is a link to a list of manuals. Look through the Beseler 67 manuals to see if your model is the same or similar to the ones shown.
http://www.darkroompro.com/pdf/enlargers/index.html
Hope this helps, and have fun!
Matt