Hi Gary
I have a Sears 25gal. vac. and I don't use the bags and it works just great this way.
I do need to clean the filter more offen but that's no big deal,the only time I need to change it more offen is when I do alot of MDF stock.
I do slip over a old pair of the wifes panty hose over the filter to make it easy to clean out.
Now for the ShopVac ,if the motor is ok I would order a new board and just replace it or get your volt meter out and see if the motor is just a standard motor and if so just by pass the circuit board and cut out the outlets on the top side all together.
I just replace my circuit board on my Mig Welder and it was was duck soup to do,they are cheap now days, 28.oo bucks for the board and 1 hour to get the job done.
The repair shop want $280.oo to do the same job but this is a big welder I guess 225 amp. AC/DC and would take a truck or a trailer to pick it up, I ask the guy why can't you just do it in my shop and he said ,we don't do it that way.
So I said new board ,6 screws and 8 plugin wires to get it up and running again .
What one man can do another can do just as easy.
Bj