I recently ordered custom retracts from CJM, Bruce was very helpful and got the design just right and fast. Although I did not use the included air valve I had my own adjustable one. I pumped up my retracts to 100 psi, 2 days later I hit the switch and they worked, 7 cycles! no leaks here. The price was excellent for a complete custom system. I will order from them again.

I did notice without air pressure in the system it is possible for the gear to come unlocked and collapse, so I made some wood blocks to hold the gear in the locked position when working on the model without pressure in the system.