orbit / Woolybugger, Have you communicated your Alpha Pioneer DC Plus tower slippage problem to Mark/Alpha/Newtech tennis? Mark/Alpha Tennis's customer service is second to none.
I have worked around several of these dropweight stringers and all have been good, quality stringers without this issue.
I believe these stringers have a powder coat paint finish which is durable and smooth - that is the good and the bad, as the bottom of the tower and the bottom of the table rail are coated as well, I think. Make sure the rail surface at the table underside and the bottom of the towers have the painted surface removed (no metal removal). Also, use a heavy fender washer (~5/16" ID/1-1/8" OD) on the adjusting knob screw (8mm?) to better distribute the force. I would, also, add an external star tooth washer to help lock down the system. Clean these surfaces as you would clean your clamps and the tower slippage issue is no more!
Good luck, keep stringin!