Hobie Mirage drive slipping (only the front fin moves)

Hello all, First post here from Texas.
I have a 2014 Hobie PA 12 and love it.

I'll embed a youtube video to clarify my issue.

I'm probably using the incorrect terminology, but this weekend, the mirage drive started to have a significant issue.
When I peddle, the front fin moves just fine, but, the rear mast + fin does not.

I'm in the process of disassembling the drive.

Other than having to bend the front drive mast a couple of times, I've had no issues with the Mirage drive.

There is a problem with the rear fin/mast assembly somewhere.
Here's the video from youtube. I should have made a second video, but, if I hold the teeth of the chain drive on the rear fin drive, I can move the fin mast freely. If I hold the teeth on the front chain drive, I can not move the fin.

My guess--there is a disconnect somewhere between the rear fin mast assembly and the drive axle?

In the video, the rear fin mast is filmed first, and the front fin mast is filmed second. I know the video only shows a subtle difference, but in the water, the rear fin does not move.

Well, think I've found the problem (two problems)

The set screw housing is cracked and the rear sprocket is sheared in half.

No bueno

Details on likely mechanism of injury. Hypothesis

7 months ago I was in a dense stump field

I thought I was out of the stump field and started peddling carefully at first

After a minute of peddling, I gained confidence and started peddling faster and faster thinking I was well clear

Now at full speed ahead and blam; went from about 5mph to zero hitting a stump teeth chattingly hard square on with the drive

Since that time there's been a subtle "click" sound when peddling

Yesterday, the clicking sound stopped just after I heard a "clunk" and only the front fin would work--would still propel forward (much slower) but with a lot more side to side rocking

Ouch! Glad you got it figured out.

Sent from my SAMSUNG-SM-G890A using Tapatalk

It was definitely a hard collision and this is a tough pill to swallow (having my hobie out of commission)

File this under why I'll never own a boat reason#27

I've ordered the 180 turbo drive to ease my pain

So a new sprocket set and spline would fix it?

Yes, spine ($25 US) and sprocket ($20 US) would fix it

But, I've been lusting after the 180 drive since they were released.

I'm not going to fight fate

nothing better than a good excuse..