Dichroic slides sticky on LPL 670 enlarger

This enlarger hasn't been used in some time and 10 minutes of exercising it hasn't totally freed-up the dicroic filter slides. They tend to rise slowly and sometimes stop short of the actual settings.

A bit hesitant in trying to remove the slides to re-lube them; anyone ever done this? What lube did you use?

I can't see spraying anything into the head; surely a recipe for disaster.

Graphite in purest form? Whatever you use has to be very stable. Years ago I had a Beseler head acting this way, it had a nearly invisible crack in a nylon part, in ended up in the trash bin.

Wound up cleaning the tracks with alcohol and cotton buds. Put new synthetic grease on the slides; very sparingly. Took about an hour and got the bonus of cleaning out the mixing chamber bay.

Works fine after exercising the white light bypass lever a dozen times.

Glad I didn't have to disassemble the head!

Taking a LPL head apart is not very difficult all it needs are small screwdrivers (cross head and flat blade) and a finepoint permanent marker. This is to mark the nylon wheels to ensure they go back in the same place when you come to reassemble. Clean all the cogs, bearings and the sliders with alcohol and lightly re-lubricate. I use high melting point grease 'cos it gets hot in there. Auto HMP grease will not harm nylon, I have used it for years without a problem!

While you are at it check the bulb holder and the 'pigtail' wires to make sure the insulation has not degraded. If they are 'doubtful' they can be reclaimed using heat shrink tubing. The wires will have to be clipped about 2/3rds of the way from the holder, the tubing slid over the top and then re-soldered. Then use a heat gun to shrink the tubing to a tight fit.

New ceramic bulb holders are not easily found but Kaiser, Meopta or possibly Durst will do the job as they all use the same bulb.