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Dec:
Remove motor. Remove worm cover by loosening the 2 cap bolts - NOT the central one, as this is merely a tensioner. With the worm and carrier out of the way, remove the 2 cap bolts in the head dovetail slot. The dec puck will now come out. Regrease, clean, whatever. Also, the worm is brass, as tends to bend - I have a spare if need be (I have quite a few GPD2 spares sourced through Steve Massey or William Ng in HK).
RA:
Again, remove motor. Remove polar scope cover. Remove polar scope bezel. Loosen 3 SMALL set/grub screws that hold the scale onto it, and then remove the polar scope. Remove the small screw that locks the scale at the top (External silver one), and through it's hole, you can loosen off the RA ring grub screws etc. YOu can then loosen the RA ring, but will either need a proper bezel tool, make one, or a large set of split ring/circlip pliers. Back it off a touch - will loosen the RA sufficiently to balance RA well.
Pretty easy really - I once "hypertuned" my GPD2 in about 4 hours - including precise worm engagement (NO Dec backlash) and spur gear engagement (again, no backlash). I regreased the whole thing and SLIGHTLY lessened the tension on the RA shaft so it could be balanced accurately.
Dec BL is an issue with these, so they need to be adjusted fairly regularly - I do it every 6 months.
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