I had the same issue - I guess one day the vacuum fell over and the spring popped out never to be seen again. Fortunately I had some misc springs of various sizes, so found one that fit. I used a flat head screwdriver to pop off the latch to the dust container. Once I did that, I put the spring in the spot where the old one was and popped the latch back in. Problem solved. This thread helped me realize what was going on, so thanks for posting the information. If anyone else is having the same issue, it’s an easy enough fix once you have a replacement spring. Took me maybe 5 minutes to do.