so how wide are these return chases? I often take the filter grill off and line the inside of the return with ductboard,
caulking 2x's at floor and sealing all leaks. just takes small person and want to do it. granted it is a tight fit..but it helps
to have someone outside of r/a handing up ductboard. if chases are tall and you can't reach..take r/a plenum off in attic
and put ladder in r/a from attic.

you just need someone who can do it.
measure inside your returns & post info.

aeroseal is a ripoff if ducts are acessable. if they would tell customers
that they can only seal openings less than 1/4" at least it would be
truth in advertising. Lots of openings are bigger than 1/4". I've put my
whole hand in duct take off cuts at plenums that were covered
with insulation.

just my opinion and experience.

what does the company say? they just can't won't do it?
probably not the are out making big $$ with little effort.

rent me a hotel room for a couple of three nights..been a long
time since I was in texas..LOL.
kinda punch drunk from 14 hour day & drive back from Lake Charles today...