Most likely a cracked gear problem on the driving wheels axle. Some small drops of super glue should fix this problem - make sure to hold down the cogs together in place for the glue to meld both of the cog pieces together. Or just simply replace Gordon's driving wheels with a spare set of driving wheels, preferably from a working TOMY Thomas, since they are easy to come by and cheap. These kind of driving wheels should be compatiable with normal Plarail/Tomica World/MR&R/TrackMaster HTC/TOMY/FP engines as well as the talk n action engines.
If this is not the problem, my other suggestion would be to ask kindly one of the other users here on the form who has a TnA Gordon, and see if they can take some images of all the parts to the engine (working of course), so you can compare your model to the components used in the other user's working TnA Gordon.
Just a side note: I don't understand why many people collect these variations of the engines, I can understand Diesel 10, Splatter and Dodge since they are different from their normal variants, but the TnA engines have less detail than the normal TS engines exuding Diesel 10, Splatter and Dodge; in short I personally don't see any appeal in the models themselves.
If this is not the problem, my other suggestion would be to ask kindly one of the other users here on the form who has a TnA Gordon, and see if they can take some images of all the parts to the engine (working of course), so you can compare your model to the components used in the other user's working TnA Gordon.
Just a side note: I don't understand why many people collect these variations of the engines, I can understand Diesel 10, Splatter and Dodge since they are different from their normal variants, but the TnA engines have less detail than the normal TS engines exuding Diesel 10, Splatter and Dodge; in short I personally don't see any appeal in the models themselves.