It would be best to use IdStorage Manager to fix it. Run IDSM and dump
the keys. Replace the 0x0041.bin file with a good 0x0041.bin file
(from another PSP with a good 0x41 key, for example). Then run IDSM
again and verify/fix keys. It will then tell you the 0x41 key in the
PSP doesn't match the 0x0041.bin file and ask if you wish to replace
the key with the contents of the file. Press X to do so. After that,
KC should show 0x41 as good.
Eventually, KC will fix 0x41 all by itself, but I probably won't make
another revision for a while yet, so the above using IDSM is the way
to do it at the moment.