I have an Exmark Lazer Z ser# 130,000+ with a 22HP Kohler CH22S. The problem is the idler pulley on the 60" deck that is running out of line with the rest of the pulleys. I suspect it's part of the reason I blew out the bottom bearing on the center spindle. When removed all looks square and straight but with tension and power applied it raises up and gets out of line. Any recommendations? It is the old style pivot arm that I have heard was replaced due to this kind of problems. The machine has about 1400 hours on it. Thanks.