rkmhd wrote:Hello all.
I picked up a mark VII a few months ago. Little did I know what I was getting into. It worked at the previous Owners house. I tried to use it at home and it would hum and not turn. So I took the headstock off. and took it appart. The belt was stuck in the shelve. So I took the belt off and ended up getting a new one. Then I took the motor appart because the wires were literally falling appart. I nipped them back and soldered in new wire with some shrink wrap. Everything seems to work pretty good. The unit does get quite loud at full RPM, and I noticed the speed selector turns on its own a little. For the most part I fixed that issue. The latest is the gearing that moves the headstock up and down. I don't quite understand what needs to be fixed on it. I can move the gear forward on the shaft to connect with the drive gear of the handle. It stayes there as long as the headstock is going down. As soon as I rotate it to go upwards. The gear slides out of place and it just sits there. Can anyone shead some light on this please. I am in the middle of uploading some pictures of the gear to see if it makes any since to any of you guys.
For "the speed selector turns on its own"
There is a metal cam follower which the plastic cam pushes and pulls as the speed dial is rotated.
The plastic cam can be installed 2 different ways on the cam follower... yes the right way and the wrong way ]11529[/ATTACH][ATTACH]11530[/ATTACH]
It is not easy to see here, but the surface of the metal cam follower which comes in contact with the plastic cam is actually beveled.
One side is thicker than the other. The thicker side should be on the top.
Both pictures show the thinner side of the cam follower.
When installing the plastic cam onto the cam follower, the cam follower will naturally want to rotate such that the heavy side will be down.
That is the wrong way.
If installed like this, the result will cause the speed dial to increment on its own while in operation.
If you are going to remove the cam from the cam follower; check the cam follower bearing by rotating it. If it is bad or going bad - replace it!!!
When that bearing goes bad; it will get very hot and melt the plastic cam.