I don't believe that there are any service centers for the Power-Trac.
These machines were made to be operated and worked on by the owners. What the owners can't do, there are service centers for the engine you have, and a hydraulic shop should be able to fix any hydraulic problems. Terry at PT can just about talk you through any problem. A good friend with mechanical skills is a plus.
If you need help, just ask the question, and I will bet some one on this forum will have an answer for you.
I believe that this forum could qualify as the actual service center for PT.