I picked-up this interesting Columbia machine the other year. It is a BJ "Imperial" from about 1904-05.
Looks like a rear-mount machine that was using-up front mount parts, which is why the winding crank is on the "the wrong side".
It has a two-spring Columbia motor, which tends to "bog" during play, then speed back up. The cycle of bog / speed-up take a couple of revolutions each way.
The thing that's got me puzzled is that the frequency of the "bog" is not with every revolution; it is spans several revolutions, and I believe it slows-down quicker than it speeds-up...
I'd check the governor mounting. It sounds like there may be some side-play so that the governor moves back and forth increasing and decreasing the distance between the friction pad and spinning disc.
Make sure the governor shaft and sleeve are clean, and that the sleeve is thus free to slide on the shaft. Old lubricant on the shaft can get gummy and so even though the governor is trying to do its job - iteratively hunting for the desired speed - the gumminess slows the back-and-forth of sleeve on shaft, thus slowing the corrective cycling action of the governor over a noticeably longer time (and therefore over multiple turntable revolutions).
While you are at it, make sure the governor disc is clean and smooth, and that the governor shaft bearings are lubricated. Try not to remove the governor in doing so, to avoid issues with end-play settings upon reassembly. Also oil the governor pad(s).
Is it possible that the big gear driven directly from the spring barrels may have some bad teeth. That gear moves the slowest. I'm basing my diagnosis on my experience with a Victor motor, I have not seen a Columbia motor in person.
I have ran into this problem before and here is what I do. This technique will work with other motors, too.
1. Make sure the motor is wound down.
2. Manually spin the spindle shaft slowly to see if there is a bind. If there is a bind, check to see if there is a bad fiber gear or any bad teeth on the brass gears. If any of these gears are bad, they need to be replaced.
3. If the gears are good, remove the governor. Make sure the disk is clean, and the springs are even and flex. Make sure every tiny screw and washer are tight. Loose springs, weights and screws need to be tight, otherwise, inconsistencies like this will occur. If the springs are badly bent up, they need to be replaced, with a complete set of three. Check the consistency of the weights. If they are different, get a matching set.
4. After the governor has everything tight, put the governor back in. Adjust the bearings so you can get a good mesh. Columbia motors are kind of tricky, and sometimes it is trial and error.
5. How to check the mesh, is to manually turn the spindle and if smooth. put everything back together. Make sure the governor shaft, bearings, brake pads, and everything else is properly lubricated. Good luck and keep us posted.
Harvey Kravitz
Phonofreak wrote:I have ran into this problem before and here is what I do. This technique will work with other motors, too.
1. Make sure the motor is wound down.
2. Manually spin the spindle shaft slowly to see if there is a bind. If there is a bind, check to see if there is a bad fiber gear or any bad teeth on the brass gears. If any of these gears are bad, they need to be replaced.
3. If the gears are good, remove the governor. Make sure the disk is clean, and the springs are even and flex. Make sure every tiny screw and washer are tight. Loose springs, weights and screws need to be tight, otherwise, inconsistencies like this will occur. If the springs are badly bent up, they need to be replaced, with a complete set of three. Check the consistency of the weights. If they are different, get a matching set.
4. After the governor has everything tight, put the governor back in. Adjust the bearings so you can get a good mesh. Columbia motors are kind of tricky, and sometimes it is trial and error.
5. How to check the mesh, is to manually turn the spindle and if smooth. put everything back together. Make sure the governor shaft, bearings, brake pads, and everything else is properly lubricated. Good luck and keep us posted.
Harvey Kravitz