If the PSU is working, then it would be very unlikely for it to be anything else. Regardless you'd need to open the PSU to find out. Just be careful as PSUs are dangerous.
ill be careful! Ive recapped a CRT recently and learned a thing or two about caution around electronics.
Need to get some new fans. Any idea if it needs to be those "square" ones or if i can buy a more common one and leave a gap?
Hrmp. Went in and poked around, moved the wires about a bit, unplugged/replugged the fan connectors, now they spin. Oh well, cheap and quick fix at least