Has anyone noticed that some voices on the T3 are attenuated when the mod wheel is used?

e.g. The "Vintage Open" Guitar case in point on the T2 this very same voice is not attenuated.

Also the same "Vintage Open" Guitar on the T3 when played (via a saved T2 Registration) on the T3, sounds quite different (naturally I've matched all parameters I can find between the two same voices to test for the source of the attenuation and differing sound to no avail).
Unless I've missed something (quite possible), I really don't know what's going on here.

Why should the mod wheel drop the volume on these voices anyway - doesn't make sense unless there's something wrong with my machine?

One theory I had is that the “Piano ‘Lid Open’ via mod wheel” is locked on somehow with these voices where it shouldn’t be.

Anyone else notice this phenomenon?
Any feed back would be appreciated.

Chris.