Gear train noise

[Waterloo]

I don't know if there are any scissor gears in there, I had one on my Injector cam that was ready to blow apart. There are tensioner springs with bolts that were loose and warn. I could never hear them though, but they had rubbed through over half of the spring retaining bolts. It was a disaster waiting to happen. We replaced with a solid gear, which was ridiculous $$$$ I want to say close to $500. I know in my 871 there is another scissor gear in that lower housing down towards the damper.

The oil pump, if I remember correctly, did not have that much if any play in the gearing, certainly not enough to be heard. I can't think of anything else down there. Unless, like your thinking a bad shim on the pump. I left mine stock.