I have a Powermatic III Model 66 table saw with a 5 HP motor. Saw motor will not start unless I remove Switch Box cover and hold down the on switch. As soon as I let off the switch it comes back out and the saw shuts down. That is to say, the switch cannot hold itself in, at the on position. I'm wondering if the entire switch assembly has to be replaced or if it is repairable without a lot of work and trouble and buying a lot of various parts? Thank you

SOURCE: My Powermatic 66 table saw won't start.

Your saw motor is equipped with a two speed internal start switch. Over time saw dust will get into the contacts and cause the points to burn. You can pull the end off of the motor and take some 400 grit sandpaper to the contacts to clean them( there are two sets of contacts one works in the out position the other in the in position) it will be the set in the in position that is the problem. Gentle clean them, reassemble the motor end cap and it will work fine. I have to do this about once a year to my saws. I use my saws about 25 hours a week. I have been doing this to one of my Powermatic saws for 31 yrs. now.

SOURCE: vibration in powermatic model 66

No. Unplug saw remove saw blade grasp shaft that saw blade was on wiggle back and forth. Should not be too much play. After 10 years motor bearings are proably worn. Easy to replace

SOURCE: Manual for Powermatic model 70 table saw

Did you try Powermatics web site?

SOURCE: I have recently purchased used powermatic 66 Table

That is the current setting for a motor-starter which is an overcurrent sensor. This is a circuit breaker like device that usually has a heater coil that opens a contact which cuts the power to the relay that powers the motor to prevent overload damage to the motor.

The dial is in AMPS and should be set just slightly higher than the nameplate amp rating for the motor.

SOURCE: need motor cover for powermatic 66 table saw

I have seen a "buy it now" on Ebay for such a thing. Someone making a vacuum formed generic cover. Looks like it would work, even if it looks like a bubble-boy-solution.
Another solution I have seen is a wooden replica with louvers for ventilation.
Sheet metal would be a solution if you have a break and press to properly form, other wise it looks like you banged it our with a hammer and scrap metal.
I need the same thing and will probably to the wood with a paint that hides the fact...