I believe my PTO switches and hardware on my TC35 are indentical to what you have on your TC33. That PTO switch is always something to pay attention to. For instance, I had that same problem years ago when I first bought my machine (back in '04). Was running it during a snowstorm, trying to get lumber in the barn before it got buried! Stopped the tractor at one point, and then went back to it 5 minutes later....The darn thing wouldn't start!! Tried what I thought was everything, and then had to abandon "blue" in the snow...
I had just become a TBN member then, so I went home and described the problem on this very forum. TA DA! Someone suggested, and I think it was Jinman (was it, Jinman, maybe you remember....), that I might have moved the PTO switch by accident. Went back to the machine, and sure enough, I had accidentally hooked the level and just moved it about 3/4" out of "true off". That was enough to pull the lever stop off the safety switch, and convince the tractor that the PTO was "on".
Moral of the story....pay attention to that darn switch (and in your case, the wire,too)!!