When I was in school at the Piano Hospital, we were issued a bungy cord for this purpose. It is a long, elasticized cord with four metal hooks on it. I first remove the keys (make sure they are numbered and that you know where you are going to put them before you start removing them), and then attach one hook of this cord to the bass action bracket, the hook on the other end to the treble action bracket, and the two hooks in the middle usually to the two middle action brackets, or, at least, to somewhere on the action. I have never had a problem getting one out or in, except when I hit a damper on something I wasnot supposed to hit (operator error.) For the Acrosonic actions, we were given four old damper blocks which we attached to the pins sticking out of the top of those stickers to make "ten thousand per cent" sure that rail doesn't come off, then use the above method.
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