nanao ms8 26a H/Hold problem

[marcus.]

Sorry, but it is hard to not direct this post almost exclusively to guru jomac!

My chassis has recently developed a fault (all of a sudden, not gradually) where there is no tolerance in the horizontal hold adjustment.
I can only just get a stable image on the screen, but just touching the pot , or even turning the monitor off and on and the image turns to crap and needs to be tweaked again.
Before the fault occured there was plenty of room to play with.

Any advice greatly appreciated.