I believe the seller may be wrong with the date on this piano... This could be an early 69 with the square felt tips which later on has been switched out with neoprene tips.
Perhaps you're right.
I'd thought the '69 Sparkle Top would have had four 12" speakers, rather than the 2x12/2x10 configuration, as well, no?
If this were a '69, might it also have had the early twisted steel tone bars, as found on my '69 Suitcase and '69 Student models?
Based on pianos I have, I think the switch to twisted steel bars came before the switch to hybrid hammers.
I think the most likely scenario is this is pre-'69 piano, as evidenced by the earlier damper and tone bar configuration, that's had its hammers swapped. I wonder if it has the metal pedestal bump?
Whatever this is, this hammer and tip configuration isn't '66/67 factory original. I guess with something this old, such swapping is to be expected.