PSR S770.......repair or just move on ? Electrical/contact gremlins.

[joeloss1]

I bought the PSR S770 new about 8 years ago (it's now my spare- I have a PSR S975). I'm a full-time senior/care home entertainer so the 770 has been on at least 2500 jobs plus home use. It has been great but now.....on/off button difficult(mainly off that is hard....press hard for 10 secs or more). Also other buttons seem to be starting to play up too/generally a bit erratic. I'm guessing this is the carbon-tipped rubber issue plus maybe dust ?

Just wondering if these keyboards have reached the end of their useful lifespan after a few thousand hours....otherwise I'm guessing it will be maybe £150-ish for my keyboard repair man.....second-hand value (fixed) maybe £300/£350 ?
Any advice gratefully received.

John (Worthing, UK).