it's clear from your pictures that your compression
post is failing.
I strongly suggest dropping the mast
and either replacing the entire compression
post or cutting off the rotted bottom section and joining a new piece to the bottom. Generous coating with epoxy
will help prevent future decay.
Once you've restored the compression post to it's correct height your door will be correctly aligned. I think you find you need to add a lot more than 1/8" as was mentioned earlier.
There is also some information on P30 and P26 compression post work
on the Pearson