Buying a mpc 2500

Hello, im going to buy a used in good condition mpc 2500 what do i need to check for if its a good mpc ? i never used a mpc. i can not buy a new mpc because its to expensive a new mpc 2500 is 915euro i buy it from somebody on internet for 550. im going to the seller home and i can test it. thnx in advance

...switch it on....check the display.....no failing lines....fine....

.....press mode and press load......scroll through the options.....does the wheel run smooth...fine.....load a programm.......done?.....go back to main page by pressing main button.....press the pad bank buttons....all react?...check the pads....turn full level off....and hit them...each one....hit them soft...hit them hard.....all work?...silent and loud....?...fine....
touch the sliders.....all run smooth?.,,..fine......check rec and volume potis...run smooth?...fine.....

if that is all fine, the rest should be fine, too.....

^^^^ This. I would also do an input/ output check.