Re: DEC axis not moving in certain position. Belt slipping. #EXOS2
Sorry, but I don't understand your problem statement. Are you saying that the DEC axis is binding in a certain position? Clutches should always be on, if the mount is under power.
If that's all it is, and your scope is reasonably balanced, then all you likely need is a bit of an adjustment. There are not a lot of moving parts in these mounts, and it is not unusual for some owner adjustments to be needed from time to time.
If the motor is running, the set screws on the two pulleys are snug, and the belt is reasonably tensioned, then the worm gear will be driven by the large pulley. If the worm is not moving, then the most likely thing holding it back is a too-tight mesh (binding) between the worm gear and the ring gear that surrounds your axis. This can happen, because the clearance between the two gears is fixed, but the two gears are not (and cannot be) perfectly round. So the goal of adjustment is to achieve the smallest amount of clearance that still avoids binding on high points between them.
I don't know what an ES pre-delivery test of the mount would entail, but if bind points occur, they will be at particular locations and there's no predicting whether a short test would actually traverse a given bind point and reveal such a problem. In any case, if all that's needed is a gear mesh adjustment, that's pretty straightforward.
If I've understood your problem correctly, then the doc in the link below may help you, with this and perhaps other things as well.--
Hope this helps...
Mounts: ES PMC-8 EXOS2, Serial
Scopes: SW 130P-DS, SV 102EDT, ZWO 60/280 Guide
Cameras: Nikon D5300, Altair GPCAM2 290M
Software: ASCOM 6.3, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer: Thinkpad x230, Win7Pro/64