I built a Peter Thiel separator for my Craftsman shop vac. Recently it's stopped working properly - I lose too much suction.
1) With 40' 1.5" hose connected directly to 2.5" Craftsman hose, I can lift a quart can easily with suction at the end of the hose.
2) With 40' 1.5" hose connected directly to the separator and 2.5" Craftsman hose going into the separator, I can NOT lift a quart can, although I can easily lift a pint can.

So I figure there must be a vacuum leak.
* The plywood lid fits so snugly I can lift the can by lifting the lid.
* But while I can not pick up a quart can, it provides enough suction to suck in the sides of my 25 gallon galvanized pail. (It pops back when I turn off the vac).

Any suggestions? (Other than brace the can so it can't collapse)

Thanks