You may get a tingle from some capacitors discharging if you accidentally touch some sections of the power board with your fingers but that's about all. To prevent this from happening, after you've disconnected the power from the player, turn it on for a few minutes, to discharge any remaining charge in the capacitors. It won't turn on of course, but they will still discharge in trying to turn it on with no power connected ;-)
Here's a link to the service manual that will help. Be patient as it takes a little while to find the file after you have passed the security check.
It shows how to disassemble the player and the belt can be seen on p.6 in the tape adjustment section.
The belt part number is Sony 3-362-989-01. Search online using the part number only to find suppliers that suit you best.