I put Axial in the same camp as any other Taiwanese engine including SH, LRP, Dynamite, Traxxas, HPI, etc.. They run, but they get smacked around HARD by the Italian stallions and some of the Japanese turds without breaking a sweat.
If I was forced to pick Axial or OS, I’d take Axial. Axial an Italian? - I’d take the Italians every day of the week. Just me though. Any of the guys I know that had Axial engines had the same issues that others had - phantom air leaks and trouble tuning. 90% of these problems stem from a poorly fitted crankshaft (bad machining tolerances) and the other 10% using a flaming hot heat range glow plug and 30% nitro.
Used nitro trucks are a gamble. I posted the same type of thing in another forum. These engines are really only worth about $125-150 NEW, so if rebuild parts are needed and cost more than $75, it’s not worth keeping and you’re better off getting a replacement engine.