Years ago I purchased an upgrade kit and then became ill and have been sidelined for quite a while in different ways. Now with some time on my hands I'm finally doing the upgrade, and it's been fun and interesting and frustrating too.
I have a 1980's model that I actively use so I figured I'd upgrade the headstock from an old 1955 unit I got for parts and keep the working headstock for a dedicated drill press. Taking it apart was fun, it had a motor replacement done at some point, had to hammer out the drive shaft assembly because it was so tight. Got that done, drilled the new holes, cleaned and painted it, and then I saw that the motor mount holes didn't line up! Yup, I had screwed it up.
I considered trying to repair it somehow but didn't like that idea so I got out an even older 1954 headstock. Yes, I pick up old units if I can get them cheap, and this time it paid off. So today I tore that one down. The quill spring is broken so I pulled that assembly also and I'll switch in the one from the mis-drilled head. I went ahead and paint prepped this one but I still have to drill the new holes. I should be able to paint later and begin the installing the new power head soon.
Wish me luck, if I screw this up I'm out of spare headstocks.