Jenny wrote:

I put a lot of coffee grounds around these plants all last summer,
hoping that would help acidify the soil. What else would help?

Powdered sulfur is best. If there are signs of chlorosis (Yellowing of
a leaf between green veins) then acidity may be increased by adding
flowers of sulfur (powdered sulfur) or iron sulfate. I add 1 tablespoon
of sulfur powder around the base of any plant showing signs of chlorosis.

More sun isn't an option here. There are about 4 hours in the afternoon
and that's it.

That will reduce the number of flower buds but is not a big problem.

Any suggestions as to what to do about eliminating those weevils? I'm
assuming they came from the garden center (which grows its own plants)
as none of my 4 other azaleas or 2 yews show any signs of damage. I've
been spraying once a month with a systemic insecticide as directed by
the "expert" at the locally owned Farmers Ag coop. After 2 sprayings,
I'm not seeing much progress. I've also hit them with "rose spray" to
take care of the caterpillars which also showed up this spring.

Leaves chewed on edges is a symptom of chewing insects. Most are
nocturnal feeders and can be found at night with a flashlight. The most
prominent chewing insects on rhododendron and azaleas are the Black Vine
Weevil and Strawberry Root Weevil. Feeding is done at night. Specimens
may be collected at night for identification. The major damage is caused
by weevil larvae which girdle the roots and kill the plant. Larvacidal
drenches may be used to kill them but are of limited effectiveness. A
more effective approach is to use nematodes. They are very effective
against weevils. Foliar sprays are very effective at controlling adult
weevils when leaf notching starts. Foliar sprays must be repeated until
no adults emerge. Since weevils feed at night, you can hand pick adult
weevils at night using a flashlight. Since weevils spend the daytime in
the soil and come out at night to feed, you can paint the trunk with
Tanglefoot to stop them, but make sure no branches are touching the
ground. Other chewing insects include caterpillars, cut worms and
loopers.

The rhodos did put out big clumps of leaves this past week, so they're
still alive.

This is a very good sign. Resist the temptation to fertilize. I good
fertilizer like Hollytone now is OK but none later.

Good Luck!
--
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Cheers, Steve Henning in Reading, PA USA Zone 6