Carved in mystic runes upon the very living rock, the last words of
Monique Reed of sci.bio.botany make plain:

For both of your plants:

Check for salt buildup in the soil. Water should run clear from the
pot, not colored.

Would this apply if I haven't been using any fertilizer?

Make sure you are not overwatering and pots are not standing in full
saucers.

They're OK on that count. They both have been doing fine for several
years, and I haven't changed anything. I give the Pothos 1/2 gal every
two weeks, and 1 qt to 1/2 gal to the other plant.

Repot, if you can, with fresh potting soil. Potting soil breaks down
over the years--loses texture and nutrients and the ability to hold
air.

That sounds like an adventure, especially for the Pothos! Do you think
either of them needs a larger pot?

Fertilize occasionally with dilute houseplant fertilizer.

Thanks so much for your feedback. They're both really nice plants, and
I'd hate to lose them.

--
Alan
"You cannot depend on your eyes when your imagination is out of focus."
-- Mark Twain