I've got a Flowering Maple:

Abutilon pictum 'Apricot'

It's not too old and has never grown more then about 1' tall. It gets
sun and is outside in the summer. It's guess it to be about 2 years old.

It gets an occasional yellow leaf but now I have many leaves, both old
and new, getting a mottled effect. See the scan below on leaf:

http://ny.existingstations.com/auctions/fmleaf.jpg

I've tried fertilizer changes, watering frequency and moving it around
to different windows. I just did a hard prune on it.

Any ideas?

Thanks,

Charles