I have a G6120 BS SSL and the Bigsby works perfectly on that, had it for years and gigged it relentlessly, perfect. I just bought a standby guitar because it was an interesting model, it's an Epiphone Riviera Deluxe Jarmo Kaukonen signature model with a B70G fitted. Even very gentle use of the B70 it puts it out of tune. It's the wound strings that are affected the most, they always return to too sharp. The strings are new but fitted by an expert in the shop with very windings around the string posts. I suspect a few things but would appreciate advice from you guys. It could be the nut, we'd all suspect the nut pinching right? But it's a 2004 guitar, surely the owner didn't put up with that for 14 years? It could be the tension bar needs a lube. It could be bearings/bushes at the bass side of the tension bar, that might explain why it's affecting the wound strings the most. Anyone heard of this happening before? The only other thing I can think of is the tune-o-matic bridge. There will be more friction on the bass side. I'll lube that too. Have I missed anything and has anyone had the same symptoms? If so please let me know. No pun intended but it's driving me NUTS! Thanks.