I have a Delta 50-760 dust collector that suddenly lost suction power after at least 4 years of use. I had just emptied the lower bag and each time take the upper bag, turn it inside out and shake/beat as much dust out as I can. When I hooked it back up to my planer, it had maybe half the suction power and the planer chips were all clogged in the Y tube before reaching the impeller. The upper bag was only half inflated.

I only have the one 4" hose running off the Y, the other Y outlet is capped. Motor sounds like it's running the same and I can't detect holes in the hose, etc. I took the upper bag off twice, beat as much dust out of it as I could and finally did enough improvement in suction that I can use my planer and router. It appears to be almost at previous power but the upper bag still isn't as inflated as it used to be.

Is the upper bag just so saturated with fine dust that it needs to be replaced? Is airflow through the upper bag the culprit?