I never have had a problem with the cylinders front or back the maching is very good, though I had problem as I have posted in the past about the pivoting shaft picking up with the bushes. As these are both made out of an alloy, one of mine completely jammed whilst initially setting them up. I changed these for phosphor bronze bushes with steel shafts which made for a very smooth running retract

Have now finished the tail plane and ready for re-install back on to the Hawk.. (all the probes keep getting in the way )

Alan