I do my G11 every year. I assume the GM8 is the same. First get a bucket, a nylon tooth brush and a bottle of mineral turpentine. Undo
everything that can be removed, turp it up, brush it and let it dry.
Get a bowl fill it in with WD40 and dump in all the bearings. Let them soak overnight. Rinse the ones in RA and DEC (the one you don't remove) with WD40 also. For the gears, get a wooden tooth pick and clean every single notch (... only 359 to go
). Get some thick white lube and apply it in all the clean gear notches. Don't put any thick grease in any of the bearings. When water gets in it gets sticky and glues the whole mount.
If you have time, get some real fine sanding paper and sand the axis shafts to remove bearing/ringing marks.
Don't lube anything you don't have to.
For the worm tightness, it's a compromise. I run the whole DEC/RA gears by hand until I got a hard spot then relax a bit then do it again until it's good all around. Takes time but it's a one off so spend a bit of time on it. The worm cover (angle) can be used as traverse to align the end blocks so they're square when you tighten up the bolts.
That's pretty much it.
Here's the
Lube - SUP31040 for bearings and SUP92003 for the gears.