ive got my md500 500 sz with trex 500 mechs and mini v bar fbl my tail pitch...

ive got my md500 500 sz with trex 500 mechs and mini v bar fbl my tail pitch control is not behaving as should its not responding to right stick commands under load so when l spool up and l give right rudder it does not respond if l give left rud it works then after left command the right will respond but wont give enough pitch to control the helicopter l can replicate the issue by light touch of the tail blade while giving right command.
funny thing the unit compansation is correct when l swing the modle left to right end to end