F225 throttle help

[markn911]

I have twin yamaha F225s that will not engage into reverse until the throttle is nearly all the way back (probably about 70 degrees from neutral) and when it finally does engage if I go a step further I'm going backwards at a pretty quick pace. It just started doing this at the beginning of this year.

Does anyone know what is causing this, I am assuming it has something to do with the throttle linkage (not sure of course) but have no idea how to fix it or even if I can?

Any help would be greatly appreciated.
Mark