Not sure how many others are having this issue, but after glueing or replacing the clutch gear with the "blue" gear in the tamiya elevation unit it
create's another failure spot. The main D shaped shaft that the elevation arm is mounted on starts to wear out the black plastic gear it goes through and
will free spin. This is only happening on tanks with long metal barrels and the addition of aftermarket metal muzzle brakes isn't helping. Anyways, easy fix.
Take apart the elevation unit, drill holes in the D shaft along with the collar on the black plastic gear using a 1/32" drill bit making sure your hole on the gear is going through the flat of the D on the gear and of course on the flat of the shaft which makes it pretty easy. I just clipped a piece of HL antenna I had laying around about 6-7mm long. Make sure it does not protrude past the collar on either side as it will hit the neighboring gear. Capillary your fav CA or a small smear of loctite over the pin opening will keep it from sliding out. Nothing ground breaking here, just ran out of spare elevation units to bash. Sorry for the awful pics. Bad camera as well as operator.