I have an older RAM 750P start box and it does the same thing yours does if I use 6v RX packs. Work just fine on 4.8v. I'm running two 6v RX packs in my Reaper and I normally unplug one of the ailerons and plug a 4.8v RX pack during startup. Then after the turbine is running I switch on my two 6v RX packs and plug the aileron back in.

Not sure if that will fix your problem, but if your running 6v, might try a 4.8v pack.

JR Gautreaux