What exactly is it doing wrong? I had an issue with the RA on my LX200R making an awful ratcheting sound. I took the plates off and found that the pillow block that holds the worm against the gear was too far away. It was easy as pie to fix. Maybe yours is out of whack. Sounds like if it's not catching, maybe the block is too far away, or not engaging at all.
Just a thought.
Too bad you have to be without the scope for another long wait. As long as you are sending it back, maybe you could tinker with it a bit beforehand and see if it's something you can fix yourself.
-------------------- The only stupid question is the one that goes unasked
12" Starhopper / Coronado PST
Stellarvue 20x85mm Binocular / LXD75 Mount
Sigma APO 150-500mm F5-6.3 DG OS HSM
Sigma 18-200mm f3.5-6.3 DC OS
Canon EF 70-300mm f/4.5-5.6 DO IS USM