Snorkel hangs, then drops when it goes about 1/2 way down. I can put pressure on the vent when it retracts and it works correctly. On its own, it hangs then drops.
After removing lower access panel and blower for inspection, now the unit still hangs when going down but also continues to go up and down. It does not stop when fully up or down. Any idea what is going on? Your help is appreciated!

Thank you Gene. After disassembly, the problem turned out to be a lose screw on the motor arm connecting it to the motor shaft. It caused the snorkel to drop and was lose enough to miss the limit switches. After tightening the screw, all is well.