HELP!!!

I foolishly bought a pair of Robart retracts (their SBDZ) for my 100” wingspan Douglas Dauntless. It took about six months from payment to receipt before I received them. Eagerly, I started to build them in.

After a few cycles – three, as I recall – they stopped working. I sent them back to Robart for repair. Seven months later, I got them back. They cycled about six times and one of the gear boxes stripped; without any load on it.

Can anyone please advise where I can get a replacement actuator and save my now very expensive retracts. It will have to be a “double’ throw extension with one arm threaded inside another threaded extension arm.
HELP!!!

Thanks