Kicking the Pan

I have a '64 FLH (stock) that is harder to start than any other bike (I've ridden HD for over 25 years, owned a repair shop and have never owned an electric start bike).
This bike often gets to a place where it feels like there's no compression (like kicking it through after both pistons go up) for, sometimes, 10-15 kicks...like there isn't enough throw to ge the engine through a full revolution...the pistons are probably going up, but then the compression is pushing them back down.
Is the kicker gear ratio different for these "later" model bikes? Did someone decide to go for more mechanical advantage but less movement?
And...if I don't get this bike to RIGHT wherethe front cyl is about to fire, forget it...it won't start.
And I have to throw myself up in the air and come down with all my might and weight!
My Knuck starts with leg only...the other foot never leaves the ground.
This didn't used to be such a problem, but I ain't getting any younger,and BOTH of my knees have been reconstructed.

not much help, but I once had a Pan with similar symptoms, In the end I gave up and got rid of it. I've never had another bike with similar symptoms

Perhaps the clutch is slipping?

Good call.
This dd happen to me witha an Indian once and I couldn't get enough of a kick to start it.
Doubtful, though.
I adjusted the mousetrap recently...can't remember if I checked the distance between the spring plates.
It doesn't slip while riding.
I'll check it, though.
Thanks.