Help! Armshell base woes  

False Alarm
I got it. I was just being a little too gentle.
But while I have your attention, might as well ask ... what's the best for marker marks on the chair?

hi
i would try alcohol, wd-40, and/or magic eraser.

Line up your handy arsenal...
Line up your handy arsenal of products and start with the most gentle.
And use a q-tip.
goo-gone, lighter fluid, graffiti-x, all will work, but start with a gentle soap
or orange-gel first. Best to not mess with the original finish too much.
Not the best advice, but i always start with the most non-invasive.
eventually
something will work...

. . .and
test each substance on the bottom of the chair first ? Or is there a different finish or gel coat there ?