Thanks guys. There were a couple of things that worried me, but it's a pretty good attempt if indeed a forgery. It looks like a possible effort to artificially age the paper as well.
I see the "J" without the switch back pointing to the "imi", the imi" itself (lacking an "m" etc), that "He" connection (perhaps the angle of the "e") and the high riding "d" not beneath the baseline as potentially problematic. Especially all together. I wonder what Mark and the others would say or see. I expect the inscription was copied from what Mark showed.
I think the whole thing was copied minus the dedication. It looks like they accidentally missed a bit of the “Jimi” portion of the signature, and the switchback as you mentioned.