Sounds like a fan problem.
Hi buddy:
Not being there to see that Kirby in action, I can only say that it sounds like you have a chipped a fan. This can also cause the bearings to go bad. Check that belt too!
As I watched you use both vacuum cleaners, my advice is this. Slow down! It's a vacuum cleaner not a race car, the best way to clean or even test for suction is one s-l-o-w easy forward pass over the carpet, then one back. Next, move to the mark made by the rug nozzle, and make the next pass.
As for the year? The kirby Classic 111 was introduced in June of 1976 and the Tradition three years later. In the Spring of 1976 I was the training manager for Kirby in Oak Park, Illinois, when the Classic 111 was introduced. In late August of 79, the training manager of Pacific Coast Kirby in San Diego, California died and I was sent to train the staff there. The week I started (September of 79) the first Tradition models were intorduced. Interesting note here, the Tradition was the first Kirby to offer disposible bags. Know why? Many a sale was lost because the prospective buyer said " if it only had a disposible bag I'd buy it!" Kirby changed with the times. Guess what the price for a Kirby Classic 111 was. $549.00 complete! That was Handi-butler, Rug Renovator, Mirical Head and Handi-Waxer.
Alex Taber