I normally just blow the motor out, they never lasted long enough to lose vacumn power. I have the following bags, Eureka Upright Style F & G; Eureka Upright Style J; Sharp and vacumns using Type PU-2. I really like my Simplicity cannister vacumn cleaner, btw.
I’m in luck! My upright takes a J!
Now all I have to do is find the leak.