Last wheat harvest our 8820 developed a vibration in the drive train. We finally got it in the shop to look at and are having difficulty isolating it. We were hoping it was in the intermediate pulley but with all the belts removed from the main output shaft the vibration still exists. The bearing seems to be tight and reaching in through the hole in the bell housing doesn't reveal any lateral slack in the spline end against the engine. There is however a couple of degrees of rotational slack in the splines. We also blew all the dust out of the pulley as well as we could. Just wondering if anyone else has had this problem and what the root cause might have been before we start tearing more apart. Thanks.