I have an old (2001?) JCB shredder. I've used it for several years, unjamming it now and again. Yesterday I used it and it stopped again, so I unscrewed the cover (single screw) as usual to remove the bits stuck to the blade. Only this time, there weren't any. A quick check with an ohmmeter across the mains plug showed the shredder was open-circuit. The fuse was ok.
To get at the motor I had to remove 4 screws (pozi No2), 4 x 10mm bolts with locknuts, 4 x 13 mm boils with locknuts, and the blade holder (13mm). I could then lift the motor shield up with the motor attached. To remove the motor from the shield another 4 x 5mm hex-head screws would have had to be removed, but it wasn't necessary. Having got access to the motor, I removed the leads, and an ohmmeter showed the motor winding was ok. However, the connection from the plug to the motor was open, so it looked like the switch had failed. To remove the switch box, another 4 x pozi No2 screws had to come out. But that just left me with a box with no apparent means of access. Eventually I got in by sliding back some locking wedges (see yellow pieces at each corner ). I've never seen anything like those before. Inside was a switch with an overload mechanism (below the black button in the photo), and I found the neutral connection on the double-pole switch was open. Live was ok. Although I was eventually able to get the switch apart (2 x torx No10), it wasn't repairable, and replacement switches are no longer available.
So that's it. I suppose I could short-circuit the switch and just use the mains socket to control the shredder, but that overload mechanism is there for a reason. Maybe I should just be content that the shredder has lasted many years; but it could have gone on for many more years.
One more thing. Lucky I've got a decent selection of screwdriver bits, spanners, sockets, etc! I wonder why so many different sizes and types of fixing were used.