Help..Zone VI Enlarger focus knob doesn't work

[trudee yama]

Purchased a used Zone VI Enlarger a couple of years ago, one of their earlier models...I love this enlarger. First my motorized focus control stopped working, an inconvenience but all I did was switch to the manual focusing knob. Then this morning I turned the knob but the bellows didn't move. Much to my dismay I rotated the knob right out of its housing. The catch is flat. Can I repair this on my own? Can the motor be repaired? My friend owns a very precise machine shop. Since these need repair, what about attaching a focus extension? While I'm at it, what's the secret to using a grain enlarging focuser with a cold light head shining blue/green light? It's only been a couple of darkroom nights since my motor broke, but between manual focusing and grain enlarging focusing with cold light head, feel like I'm beginning to sprout a hunch back.

Thanks plenty, you guys are a best source for trouble shooting and information.

Trudee