when u push the botton from a certain angle it works better
that really clears things up - that's enough for me to diagnose this DEFINITELY as a worn sensor issue. how long/how rigorously have you been using yours?
the bad news is that you have to order a replacement piece/soldering gun. the good news is that once you learn how to do this, your mpc1000 will be virtually ageless. there is not one piece of hardware in the mpc1000 which will break in the forseeable future that costs more than 10 dollars to fix.
this does not include the screen, which is more expensive - and also has a looooong life. don't worry about the screen.
as for pads, buttons and data wheel, it's all cheap (cost and manufacture). we're lucky to have vst.
that being said, it took me a year and a half for my DW to start messing up, and nearly 2 years for my button to start messing up. i'm happy with that, especially given all the people crying about how the "mpc1000 feels like a toy."
honestly, i'd rather do minor repairs on a piece that i spent 700 on and can carry in a small bag than anything more expensive