Does the support slide freely without the bolt installed? Binding somewhere? Look for scratches on the support body. Also look to see if the handle slides freely in the slot on the tube. During welding, this can warp and pinch the slot. To fix, take a large flat blade screwdriver or something in the slot and twist to widen it a bit. Make sure there aren't any weld burn throughs at the tube/ receiver junction. To fix that is a bit more of a challenge. Lastly, make sure the bolt goes in and out of the trunnion smoothly. If it binds there. it is much more difficult to fix

 

Remove your suppressor and see if the weapon still has problems cocking if the weapon no longer has problems then the cocking handle support will need to be adjusted to not hit the suppressor

 

^ this. Your cocking tube support may be binding and scratching against your suppressor. I had the same problem and ended up installing an SD cocking tube support with the relief cut, RCM sells them (RCM SD COCKING TUBE SUPPORT - Rim Country Manufacturing) or you can just cut your OEM one down to get the clearance needed.

RCM SD cocking tube support on the left, MKE OEM non-SD cocking tube support on the right (which came on the AP5-SD)