Simple but super effective, thankyou.

hello! I cpouldn't make out which were the bolts I need to unscrew to service a similar HP-1800e digital piano. Could you specify somehow? Cheers!

I have sticking keys for hp 2800 roland. do you have video on that?

I've got a HP1700 that had some sticking keys and also two keys that only play the notes at full velocity. As for the sticking keys, I just took them out, cleaned them with 70 percent alcohol, relubed the moving parts with vaseline and they are working fine now. As far as the velocity issue, I noticed the circuit board underneath the thin grey rubber velocity trigger thingies. You can look there and see which one triggers the high velocity and which one triggers the low velocity. I traced the low velocity circuit on the board and instead of being green it has a bit of a blue hue, which makes me think that circuit trace on the board is oxidized and the connection is broken there, because copper turns blue when it oxidizes. In your case, try using testing the continuity between the velocity triggers under the grey rubber, and a couple inches away were they reach their destination at the solder joint. If both of those circuit traces in the circuit board are bad, that may be the cause of no sound. Sorry if some of my terminology is off. I'm not an electronics expert.

Hey did you ever figure out the keys that didn’t play sounds? I just picked up a free one and it works brilliant except there are two blocks of about 5 keys each m-one on the very high notes right hand side of keyboard and one just on the left of middle C-both black and white keys all in a row that don’t have sound. I’m gonna take it apart like your vid and see what happens. Hopefully it’s just the contacts and not the motherboard. Let me know please! Thanks for the vid!