When you take the cover off the front of the vac you will see the control valve to the right. There are 2 screws that hold it in place. The valve will shut off early if the screw in cap is damaged (the plastic is broken holding the O ring in place). Mine didn't function at all, so there are things to check for
1. pull the tube off of the nipple on the hose opening going to the bag and run a small wire thru the nipple to see if it is plugged. Make sure to put the tube back on the nipple after you checked it.
2. Take the valve off of the plastic base plate, then unscrew the cap, check the little plunger to see if the valve is stuck. Check to see if the plastic is broken holding the O rings in place.
3. Check to see if the diaphram is ok.
4. Check to see if the rubber seal between the bag housing and the front cover is ok.
When you put the valve back together, screw the cap back in till it bottoms and take the dial fitting it into the plastic tab on the valve making sure that the alignment marks on the cap and the dial line up ( you may have to back off on the control valve knob to get them to aling). Then fit the other end of the dial into the hole in the post of the front cover. Fit the control valve back into place, then screw the valve on to the backing plate.
In the case of my Golden J (model 1205) the plunger was just stuck in the control valve knob. Also the brass nipple was plugged with junk.
Here's a diagram of how some of this goes together.
As to the Check Bag light, the contacts were just dirty and needed to be cleaned on mine. That switch hasn't been available for years now. I've taken a spare switch off a dead Super J parts machine.
Hope this makes sense and helps
