Here's picture. I pulled the "gasket" up to show the offset of the antenna in the hole to see that there's no way (that I can see anyway) to push that lower "skirt" gasket in the hole with the antenna in place. I can get the gasket in the hole without the antenna but it folds over on itself once it's in the hole. I tried different "lubes" and nothing.
View attachment 202786
I dunno if this'll help much, but for whatever it's worth.... :dontknow:
You can see the hole in the panel isn't symmetrical, and the recessed collar that's between the wide base flange/skirt thingy & the bit of gasket that's left sticking out of the top of the panel is shaped to match that hole - I have a somewhat vague (possibly deliberately blanked??

) recollection of being extremely frustrated in much the same manner you're describing, until I lucked on the 'trick' (or fluke?

) of feeding the wide flange/skirt bit in deliberately out of sync with the hole shape while twisting the whole gasket by the top bit (the bit that's meant to stay on the outside of the panel

) so that
juuust as the last bit of the flange/skirt got pushed/twisted down thru the hole, the angle on the recessed bit moved into its final matching position in the hole... While ever the odd shape of the recessed bit of the gasket didn't match & fit
EXACTLY into the odd shaped hole, the gasket flange/skirt wouldn't go in/stay in - it
ONLY worked once the very last twist & bit of a push in brought the odd shapes of the gasket's recessed collar and the hole into alignment that it finally sorta '
clicked' down, fully in, and into place.... If any of that makes any sense to you?!
And until I did that one, I thought it was a pain getting the antenna gasket on the earlier RT's to fit!!

So after that ^^, the next time I got asked to help with fitting one of those bloody antenna gaskets, I piked out - too hard! (that's one of the few joys of being TPI Retired - being able to pick & choose what you wanta work on!

pps: ) But I did suggest that while I didn't know if it'd be any better &/or easier, they should try "
taking half the bike apart to get to the backside of the mount", lubing the gasket up, & feeding it up from the underside.... :shocked: Only I'm not sure that it worked that way either - I'm pretty sure that I've since seen
that particular Spyder with an antenna that now has the wide part of the gasket flange lightly & neatly siliconed to the
outside of the panel! :shocked:
Mind you, if you're open to it... another alternative that I now
KNOW works, is to get & fit one of the a/mkt Shorty Antenna's, I think Lamontster has them - they at least have a gasket/grommet/boot thingy that fits & seals a whole lot easier, and the shorter antenna doesn't get in the way anywhere near as much! :thumbup: