Mark V 500 Repair Questions

[stevea]

I am a new owner and new poster. I was given the above machine. It was made in 1982. The previous owner said the motor had problems and the speed control handle was broken. I have partially disassembled the powerhead. Here is what I found:

1. Motor - the problem was the spacer behind the fan sheave. It was gone. This caused the fan sheave to rub on the motor and also caused the motor belt to fray. With the fan sheave removed the motor runs but is a little noisier than I would like. If I turn the motor shaft by hand I can feel/hear a little rubbing. I suspect a bearing. Does this sound correct or is a little rubbing normal? The fan sheave appears OK so I think all I need is the spacer and new belt for that part but still wonder about the motor.

2. Power head case - where the speed control assembly attaches the screw hole where the dial screw goes into is broken (See image # 1). Will replacing the screw with a small bolt, washer and lock nut work or perhaps forming a tab with JB weld?

3. Quadrant assembly - it has the typical problems that have been described. The quadrant assembly has some bent teeth (Image 2). Should this be replaced or can I file them a little or should it be replaced?

4. Worm Gear - it is boogered up (image 3). They used some vice grips to try and turn it. The worm gear shaft is catching in the brass bushing that it goes through even with the bad end sticking all the way out. I know the the worm gear needs to be replaced but I am also worried about the bushing in the control bracket. Should I just replace the whole speed control assembly or try just the worm gear?

5. While I have it all apart is there anything else I should replace or upgrade?

Thanks for the help. I am sure I will have more questions.

Steve

[BigSky]

I am barely able to keep mine running so I am not going to offer advice on how to repair yours but I know that you will receive help. I do think you need to bite the bullet and buy a replacement quadrant and speed control.

I don't have much experience with JBWeld but there is not much to work with on the broken out screw hole. If I had it to repair I would create some sort of backer plane that I could JBWeld to the inside of the housing while building up the outside where the screw goes. The excess could then be files down to be smooth with outside.

I said no advice, didn't I.

Welcome to the forum and good luck with your repairs.

[jimthej]

As badly torn up as the shaft is, my inclination would be to replace the entire control. The first deciding factor would be the ability to clean up the shaft and still have the set screw find its proper dimple. The other factor is how smooth and easy the worm gear turns in its bushing. Too tight or too loose would have me replacing the entire control.
The quadrant is repairable. A few strokes with a fine triangular needle file is all that is needed. If you replace the entire control, save the quadrant for later use, it may come in handy.