It looks like we both have the same approach to maintaining these chassis for longevity. I've also seen the armature bearings 'glued' to the shaft and slowly coaxed them back to life again.
For a long time now the first job I do when I purchase a diesel is to pull it apart. It just isn't worth trying to run it as there is probably going to be something wrong somewhere with it and as you mentioned the oil has probably dried out and the grease hardened.
The pads that limit the armature end float seem to be made of fibre and I would be interested to know if metal (brass) ones are available which would last longer.
