I had an A1000 back in the day with the same exact problem. Wasn't sure at the time if it was a defective/warped switch, but I think it might be a dirty switch. My A3000 drive mechs, which might be the same or similar have the same problem. Blowing compressed air onto the switch while pushing it up/down with a small screw driver or blowing it with contact cleaner seems to help a lot. But the best way would be to open up the switch and clean it out thoroughly, I tried to dop that on one of my A3000T High Density drives and I ended up ruining it.
