Here's one I took off a bud's car....notice the rubber sticking out....you took the next step...

They dry rot and lose their bond between the 2 rings...
With your mods on an old stock unit, it was onlt a matter of time...you lucked out actually...some guys have busted stuff up bad from a balancer taking a dump...
The balancer is located on a keyway with a woodfuff key to position it.. you'll need a puller to remove it...air gun will be nice to get that bolt out...15/16s I believe...
I scammed a new Romac for 185.00 in the Corral classifieds..check out the stocker, rubber hanging out of it..