Its an early USA model with the bulky square plug that that has lost one if its directions.

Moves vertically but not horizontally. Other mice work fine on the computer.

I gather that optical emitter/detector pain has failed.

The optical pairs are built into the internal roller assembly

Difficult to strip down it seems. So a swap of the entire internal assembly is necessary?

I have a few other working models.

One is a made in japan rounded corner plug type, and one is from a IIe.

But the internal structures are different so simple swapping of the assembly isn't possible.

Any tips? Thanks! :b&w: