8970 remotes

I have an 8970 and ive got two sets of remotes that after some time of use they hydraulic lock and I cannot move the lever. ive replaced the male and female couplings and the cables are free and not seized. I rang the dealer and he said that youll need to rekit the detend section of the control valve, has anyone had this issue and did resealing the valve fix it, I was thinking that the valve is worn in the housing too much and internally leaking making it lock

any advise will help

regards

8970 remotes