Today I installed the new door check I got from Moss.
After first detaching the old check from the door I was able to open it--the door--far enough that I could get at the two screws attaching the check to the A pillar. In examining the new piece it looked to me that the old one could somehow be manipulated to come out of the hole in the pillar and the new one installed in the same way, but no matter how I turned and twisted the check it would not come out and while manipulating it while holding it with a big hemostat I ultimately wound up dropping it and it fell into the void behind the pillar!
As I posted yesterday there are some disused speakers in the outer footwell panels and by removing the speaker I was able to reach into the void, extract the old check and then hold the new one in place so I could get the mounting screws in place, and I then attached the arm of the check to the door. All of this took about an hour.
I must say that I am not at all happy with the new check: Whereas the plate of the old--no doubt original--check had a bead pressed around its perimeter to stiffen it the new one did not and though the plate is firmly attached to the inside of the pillar it flexes a bit when the door is closed. (Perhaps this will go away as the check wears a bit).
If I had to do this job again I would probably enlarge the hole just a bit to allow the check to pass through it, making its R & R a much easier job. Alternatively, I might install the check on the rear face of the A pillar, as the face of the pillar would serve to keep the check's plate from flexing and once it is painted out it would not be very noticeable.
Anyway, taking my age into consideration and given how long the old check lasted, even with the new unit's weaker construction I am hopeful I will not have to do this job again.