Anything that removes the Dingotone will also be capable of lifting the stain, so AFAIK there isn't any magic solution that can do one without the other.

Covering the Dingtone with another finish may give you a hard surface, but be aware that it may possibly still remain soft under the surface (I've had this when using two types of finish). I believe Dingotone does contain linseed oil, the same as TruOil does, and the hardening agents in TruOil may trigger the oil in the Dingotone to polymerise properly, so you may be OK. You could take the scratchplate off (I assume this is your JMA-1) and try the TruOil on a patch where it won't show, and let it cure for a few weeks, then see if you think it's all gone hard on that patch. It shouldn't give if you press down on it lightly with a screw head. if it creates an indent with a ridge round it then its soft under the surface.

If soft, the only really 100% safe way to do it is to sand the finish back to bare wood and start again, using a different product.