40' Sedan Bridge - shower door leaking onto head floor

[Ray 40]

In my 1997 40' Sedan bridge my master shower is leaking at the bottom of the door onto the head floor.
It appears the rubber strip gasket across the bottom of the door is loose/torn/floppy and must be where the leak is.
Has anyone had this leaky problem? How did you fix it?
It is not obvious how the door comes off - looks like a big job.

Thanks for any tips you have.

Bud