Telescope Reviews: Advice - Lubricant for mount and drive gear play

(I posted this on the unitron Yahoo site but thought I should also seek the advice of CN members, too.)
Can anyone help with the following?
1) I have just 'finished' restoring my 4 inch Unitron and now need to clean and
relubricate the polar and declination bearings. Could anyone advise me which
lubricant to use. A friend has suggested using a silicon-based lubricant (spray
on)... would you all agree? The lubricant I used a few years ago was rather
viscous (can't recall details) and at the time I did notice that the axes did
not rotate as easily as I would have liked and have I wondered whether this was
imposing undue work on the synchronous motor?
2) How much play there should be between the gears (large large wheel on polar
axis and worm) when correctly meshed? I can't seem to adjust the off-axis worm
cam (if that is the correct term) to eliminate 'slack' without meshing the gears
to the extent that it is all too stiff! At present I have a swing at the end of
the declination balance rod of about 0.5 cm (hope that makes sense!)
Any advise most welcome.
Many thanks
David

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David Johns

CPC-11 (since May 2007)
4 inch Unitron 152 refractor (60s/70s vintage)

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