Intermittent problem with LADO e-retracts
 

Don't know if this problem is specific to my LADO RS999 retracts but sometimes one of the mains (not always the same one) doesn't always cycle up or down. Sometimes it takes 3-4 attempts for the retract to move. I've tried using the Spektrum signal booster to no effect. Anyone else get this problem with LADOs or any other large retract brand and solved it?