JPG wrote:The two spring loaded detent 'thingies'(bullet nose shaped) have lost some tension with age.
The 'notches' on the back of the speed dial can get their edges mashed.
Are you sure the cam follower(the part with the two pins on each side) is installed correctly(it is easily reversed).
Is the speed control dial tight to the shaft?(both in/out and 'wobble')
So do I need to tighten up the spring loaded detent thing on the sheaves for the motor? That will not help
The notches in the speed dial are clean and smooth. I cleaned them when I put everything back together.
The cam follower is on the right way and the speed control dial is tight to the shaft and to the power head.
The only thing I can think is that I have the idler adjusted too high and it’s making the belt “too small” so it tries to pull itself into high speed in order to relieve the tension. That is not likely
The tension spring on the motor shaft is necessary for the floating sheave the do it's job. The tension provides sufficient closing force on the floating sheave to prevent the motor belt slipping. If it is indeed forcing the belt to the inside of the idler pulley, it is performing as it should.
The control sheave(the movable sheave the control cam moves) pushes against the cam follower while the belt tension is providing that force. That force tends to cause the cam to rotate(towards fast). Only the detent pins and the dial notches provide resistance to the cam rotating.
The position of the notches relative to the detent pins is critical. The detents(both of them) must be perpendicular to the notches(the dial must be parallel to the headstock surface(for reference). The dial must be close to the headstock surface(the detent springs more compressed)._
The detent springs and the dial notches are places where too much lubrication will work against proper operation. I am not suggesting NO lubrication, but too slippery will cause your problem.
Time has likely decreased the force of the detents and created a tendency to 'auto increase speed'.
When you push in on the dial, will it move towards the headstock? If so a shim washer between the dial and the retaining ring MAY help. That will increase detent force.
I had a similar issue with my MVII which was corrected by a less worn dial and shaft. The dial was wobbly on the shaft.
BTW what motor belt are you using? OEM? If not, what?