HP-65 1333A20064 serviced by someone ?

[albertofenini]

Card Reader done !
The gummy wheel has been replaced with a couple of o'rings and those
have been glued together since when they are not they tent to separate.

The coupler has also been rebuild and the unit reads and writes nicely.

We are not fully satisfied however because since when the coupler has been rebuilt
the sound of the motor has changed

If you listen to the audio of the two clips uploaded in the album
you'll notice that is not continuous but rather sound like a wave
high and low high and low and we suspect that it could be because of two
reasons : the coupler is not perfectly centered or the o'ring are not perfectly
rounded, but it sounds like is not on the right axe ... what do you think ?

Any idea or suggestion is very welcome !
Thanks in advance !!

Pictures and video here : HP-65 1333A20064 updated