Combines feed conveyor drum height on R52

Are you talking about the studs that retain the height adjustment blocksIJIJ

Sorry I was late getting back to you. They are a 5_8ths by 2"

We have never had a problem with those working loose. You mentioned a problem with bunching in the rotor. There could be a feeder house problem that is causing both the bolts to vibrate loose and be related to the threshing problem.

I have a 1997 R42 and have the same problem.

It is hard to believe them bolts could come loose without very noticeable noise coming from feeder chain. I would get yourself a shock kit and leave both front and rear in grain position so chain will find it`s own height for the amount of crop coming in. I believe the 1997 is to be campaigned to install shocks and the 1996 will accept kit also. We have been leaving drum stops in grain position for all crops,even corn, ever since installing shocks a couple years ago and no problems. Be sure you have rear feed drive sprocket stripper in place for corn and front may be nessasary also but I would remove for most other crops.