I guess that would indeed be a good solution. Even if I can find a replacement it would be handy to repair the old one just in case. I'll go search for such a screwdriver now. Any idea what size it has to be?
Interesting idea, the connectors for both the XT and AT power supplies are indeed the same. However, do AT power supplies fit physically in an XT case? I'm not very keen on drilling some extra holes in the case, so if they really don't fit I'd have to use the power supply externally. While this isn't the most elegant solution, it should be easier to find such a power supply. I'll keep it in mind when I spot such a power supply.
On a side note, I might have found a complete IBM XT clone which has a power supply also suitable for my XT! It contains some nice extras like an MFM-controller and harddisk as well
. Hopefully I can work something out with the seller.