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My HEQ5 back in the day was a bit of a rough one when I got it. It had a lot of backlash, a lot of wiggle in the gears, big jumps every 638s (the worm period, which, if you're doing 30s subs, is every 13 subs)...
When I started astronomy I thought equatorial mounts were a very complicated, highly specialised machine requiring extremely specific adjustment by professionals... Trust me, they're not... Simple. Simple machines..
Having never opened anything like an equatorial mount before, but armed with Astrobaby's guides, and the instructions for my Rowan Astronomy belt kit, I took on the task of doing a full tune of the mount.
I stripped it down as far as I could, cleaned and regreased the main RA and Dec bearings, replaced all the bearings around the worms, fitted the belt mod, re-meshed the worms to a much higher level of accuracy than they were before... I threw an ADM saddle on it at the same time just for completeness, and removed the hand controller port, replacing it with an internal USB port with EQMod electronics in the mount.
I was scared the first time I powered it on after all this work - assuming for sure that SOMETHING would be wrong... To my surprise, I did a drift align, and thought for a laugh, I'd try a 60s unguided image just to see how much better or worse it was.... It was spot on.. So I went to 120s... Still fine. I went to a 240s and it showed a slight elongation, but still WORLDS better than I'd ever achieved with the mount prior to the modifications.
Granted - this was with a 380mm focal length... a little 80mm f/6 scope with a .8 reducer.. so not exactly pushing the mount at all.
When running with the OAG and guiding, I did many 600~1200s subs on that rig for a number of years, not one single isssue with it at all.
Moral of my big old story..
Even when you're not completely comfortable with doing something yourself, if you read instructions before you start. then follow them carefully during the proces, double checking each step as you go - nothing is insurmountable, and with something as simple as an equatorial mount, if you follow the instructions for what you're attempting, things really can't go too far wrong... Worst case, you have to loosen two bolts, adjust a grub screw a touch and then tighten the bolts to adjust the worm mesh.
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