Victor,
Welcome to owning a T40-C...I also bought mine as a second owner through a dealer that had to repossess it. That was back in 2008 when the economy had turned down and many high end coaches were taken back.
I have many contributions on this site about the little upgrades and some maintenance I have done to my unit -- the thing to look closely at is the undersides of the slides for any rubbing/wear on the fabric. On the vanity slide, I had metal skids added by Elite Coach Renovation (very skilled ex-Marathon guys in central Oregon...) and I also had new UHMW guides under the main slide shortly after I purchased the rig.
I replaced all the original TV units with full HD capable units with HDMI inputs in 2008, and as yet have not gone UHD but if you do anything with the entertainment system now then that is a good consideration.
I also elected to replace the original transfer switch with one that has a built in surge protector even though the original was fully functional. I chose to replace the inverter with a Magnum pure sine wave inverter as well. Lastly, my wife wanted a washing machine with more cycles than the one that came with the coach, so we put in a Maytag some time in 2008 as well (taking the washer out the front door was quite a feat.)
I have under 12,000 miles on my coach at present, but use it for essentially full time living as it is berthed near my work here in Oregon, while my home is in Idaho. I work here at least 2 months out of every three and keep the coach hooked up and livable at all times.
I think you will enjoy your Tour Master -- please ask any specific questions here.
Chuck