Hi all, I wonder if someone could help me, I have been given a Roland HP-1, the problem is that all the how to get the keys do not work, which indicates damaged hammers . I have looked at looked at the youtube videos , I thought I can do that! So i have exposed the keyboard, the plastic release tabs at the rear are different from all the the ones one film , there is a square hole with a orange tab, which I assume you press to release the key, I have tried to push them down, prise them up, I do not want to be heavy handed, Is there some trick to release these