HP-67 Card Reader became very touchy

[YoungerThanThat]

The card reader on my HP-67 was working perfectly. I would get an error reading once in a while but it would almost read a card correctly.
Now I have the opposite condition. Most of the time I get an error message and a card is read correctly once in a while. It seems that something is no longer adjusted properly.
The wheels have been changed a couple of times, and a card running through seems to have no problem.
Is this a common issue? Is there someone that could fix my reader (for a fee)?

Thanks for your help,

Michel