TI-59 card reader repair

[albertofenini]

Hi everyone

we are trying to make two TI59s reliable in reading and writing the cards.

These two units are made in the USA and we have discovered that the card reader assembly
is slightly different from those made in Europe (which we mentioned in our previous posts)

We'll post some pictures soon as it may be useful to someone

However, the gummy wheel is not gummy so mechanically speaking both
are okay, we have tested that a card can go thru at regular speed with no
issues, we are planning to clean the gear box but more because we want to see
what's inside that because is necessary....

Given that mechanically speaking the are okay, the problem is that they read correctly once in while ...

First question is : what can we check out of the obvious?
Second question : what kind of waves should we expect at the head terminals, or at the TMC0594 and at the LM324 pins ?

We have the Service Manual but there is only an example of the curve while writing a card (pag. 46)
Could be the problem any of the capacitors ?
Or could it be the soft pad that is not keeping a good pressure on the head ?
Anyone has fixed this before ?

Thanks for sharing any idea and/or suggestion !
take care !