This is base on my own experience in repairing over 300 headstocks to date. I have worked with headstocks of all ages, from 1953 to ones even a year old. The older it is, the more likely it is to need more parts. Storage conditions also affect parts and amount of usage too. Lack of use is often worse than regular usage.
The parts which are most often replaced
Control sheave bearing
Headstock locks - rarely needed
The occasional fried motor
A broken fan sheave
|
Part
|
Percentage of machines |
| Drive sleeve bearings |
Virtually 100% |
| Quill bearing(s) |
90% |
| Control sheave bearing |
50% |
| Idler
shaft |
25% |
| Gilmer belt |
75% |
| Poly V belt |
50% |
| Drive belt |
50% |
| Speed control handle |
10% |
| Quadrant |
30% |
| Switch |
5% |
| Cord |
5% |
| Motor
bearings |
50% |
| Motor |
5% |
| Headstock casting |
5%
|
Belts can fray, delaminate, tear, distort, become brittle, or be worn too narrow.
Screws, clips, washers, springs and other tiny parts can always be missing.
Bearings are always needed!
I have replaced virtually all parts in doing over 350 headstocks so nothing is guaranteed to be fine. I tear down a headstock completely to inspect all parts. Machines are frequently assembled wrong, too, whether by factory error originally, or by a previous owner working on it. So you can't take one apart and put it back together the same way. I've seen too many factory errors!