Got a problem with the EBB on my Swift.
Each time I adjust it so that the chain isn't flapping too much (I'm running it singlespeed) about five mi utes into the ride theres a 'crunch' and it slips.
I'm allowing for aN imperfect/non circular chain ring by checking tension as I turn the pedals before I tighten it up. There's still a little slack even at the tightest point.
Is it just a question of doing the locking bolts up even tighter?
I found on my Santa Cruz Chameleon EBB I had to grease every thing well then it all tightened up fine, dry it was loose ish.
Have you popped the eccentric out of the BB shell? MIght be worth checking to see if the surface the bolts tighten down onto is scarred. Also, what do the ends of the tension bolts look like? The ends that go into the shell, mind. Do they have a dimple in them, or are they flat? Dimples help grip the shell nice and tight.
My (educated) guess is that the grub screws that hold the EBB shell in place have worn a pit into the EBB shell. When you make a fine adjustment then do up the grub screws they work ok for a bit then settle back into the pits they've made loosening your chain again.
Fundamental problem with this style of EBB and why the Bushnell style is considerably better imo