Fastrak steering arm replacement

I have a 2007 model FasTrak 42 inch cut mower and I have noticed play on both steering arms (feels sloppy) and noticed that they seem to be worn or "wallowed" out, especially on the left side. Left side had enough play to put a 3/32 shim in it to keep it snug. How hard is it to replace them?? Best place for the part?? P/N appears to be 797753. Thanks in advance!!!