Toro timecutter Zero turn deck noisy

Hi I have a Toro Time cutter zero turn mower that has a mower deck that is very noisy when engaged. The original Briggs & Stratton engine I believe was a 16.5 hp engine that went bad. The Toro dealer replaced that engine with the B&S model 310000 19hp engine because the original engine is no longer made. The dealer had to use the old engine stator, engine clutch and pulleys on the new engine. I have about 2 hours run time on the new engine. It runs beautifully and is quiet. On the other hand when I engage the deck it is very noisy. The deck was quiet before the new engine was installed. I have not been able to contact the Toro dealer because they are closed for the Thanksgiving holidays.
Does anyone know what might be the reason for the noisy deck? I have looked at it closely and do not see any obvious problems.
Thanks,
Bob

Toro timecutter Zero turn deck noisy