The assembly comes out from the top, and the surrounding plastics and elements have to be removed first. Once you get it out, the assembly is not complicated and quite obvious how to disassemble. The 2 wheels are only held onto the shafts by the E-clips. I suggest taking the wheels off and do a thorough cleaning on everything, DO NOT use any lubricant anywhere when reassembling. And regardless of how old the belt is, replace it while you have it out. Refer to the manual to ensure the path of the belt is correct, the last guy to replace it may have routed it around the pulleys incorrectly.