Lets look at the main factors that contributes to inaccuracy:
1) Your
2) Your drives have “play” (this is felt when the clutches are locked and a small amount of movement is felt when you gently rock the
3) Your drives have not been trained properly.
4) Battery or axillary supply voltage are not kept on or above 12 Volt.
Getting your
The drive consists of a motor and gearbox that drives a worm gear that drives a 154 tooth spur gear. Your drives are mounted with two heavy duty screws, the one is a pivot screw and the other a block screw, the drive must be securely mounted but must still be able to pivot freely. The worm gear has a Allen screw on the end of the worm block to adjust the endplay, this screw must be adjusted but before this is done remove all the old grease and grease the worm with white lithium or another suitable grease. The grease needs to be very tacky and stable so none of it gets into unwanted places like the optical decoders next to the motor. After the shaft is well lubricated force some grease down the Allen screw hole before inserting the screw. Tighten it till it reaches the shaft and then loosen it about a 1/8 turn. Degrease the spur gear teeth and grease with fresh grease. I rotate the dive after assembly for a full rotation of the
Drive training eliminates the effect of “slop” introduced by the gearbox. This needs to be done to maintain accuracy because the encoder is coupled directly to the motor before the gearbox. When drive training is done the motor rotations needed, before the spur gear moves, are measured and given a training value. Every time that drive changes direction a certain amount of rotations are disregarded by the Az and Alt counters to maintain accuracy. So if training is not done accurately the mount will become less accurate every time direction is changed. Use a fixed terrestrial target and a astrometric eyepiece when doing drive training. I recommend that you use patched firmware obtainable from https://www.stargps.
I have never used c-type batteries to power any of my LX90 scopes but have been using rechargeable 4.5 Ah 12 volt batteries. The axillary power input plug can be improved on and I am considering installing a heavy duty plug to the internal batteries wiring, because I don’t use them. In the meantime I have secured the plug with Velcro on the wire and scope to make it more stable after I had some problems with it that that resulted in voltage drops.
I included information and photos of one of the drives :