The drive had read a directory, so it isn't missaligned at all.
Sometimes, due to some disk errors, the drive get lost. Ok, it sounds a bit crazy ...
The drive park at track 18 when finishes its work. Track 18 is the central track which hold the directory
If the drive didnt park at track 18, because it hanged, even powering off and on will not solve the problem. The head remain over a track different form the directory track and will fail to read the directory data.
You can:
1) format a disk. This will force the drive to bump the head and initialize its position.
2) initilize the drive. This is acomplished with 3 BASIC instructions
OPEN15,8,15
PRINT#15,"I"
CLOSE 15
3) Usign an alligment program you can initialize the drive and also check the alligment in all tracks
http://home.comcast.net/~safeharborbay/tcr/cbm/1541.html
Check the software at the end. To transfer it to the 1541 you will need the famous X1541 cable ....
Its a good tool, because you can connect the drive to the PC, transfer files and format disks through a DOS soft called star comander (a sort of Norton Comander). The cable is a MOST in order to put in the 64 all the games and soft avaiable on the web.
Finally, try several disks. Old disks are 20 years old or more. They are likely to cause read errors and force the drive to bump the head. If the drive does it several times, it can go missaligned.
The alligment process is very hard and complicated. I tried this in one drive without any success. I worked for hours on it. Eventully I got it working but it stoped working later and never come back again =(.