Check the push bars and pins. Excessive wear will cause the deck to pivot to the side.
Make sure the guide is on the spring loaded idler arm and, while in the operator's position,
is at about 7-8 o'clock
The same guide #108-7220-01 can be installed on the opposite idler.
Engaging PTO at any other than full rpm's will cause problems in some cases.
And I'm not getting into a debate about the last statement.