I have a TT Pro .46. Its a VERY nice engine, even though I got it free, due to a disasterous ingestion of a bit of metal causing the crankshaft to "weld" itself to the case... I had to drive the crank out, polish off the aluminum that had adhered, and clean out the burrs from inside the case. ( I had told its owner to send it in for a warrantee replacement... he just handed it to me...)

I imagine that the piece of metal it ingested was mold flashing, not cleared properly at the factory... A relatively rare problem with any brand... but the reason I advise lookng in the engine and checking for metal filings.

Another option is the Magnum .46 XL. I've got the .40 XL, which only differs in the cylinder dia, same case casting as the .46. This has also been a very good engine, easilly outperforming the O.S. .40 LA, and almost as good as the FX, at close to half the price.