Water draining from my Filter when pump is off

I have a Jandy DE filter with a pretty basic backwash valve (push / pull type)

I noticed last Fall that when the pump shuts off (after a cycle) that I can hear lots and lots of water leaving the filter and running into the pool. I have a sight-glass in the return line that I can see the water running through.

When the pump comes on there is a lot of air in the filter that needs to be bled off.

About this same time I started to notice water running out the backwash line when the pump is running.

I'm concluding the two are related, since I don't see any leaks anywhere else, there must be a leak in the backwash valve letting air into the system and partially draining the filter when the pump shuts off.

I've removed the valve, cleaned and lubricated the o-rings, but the problem persists. In fact it's getting worse. When the pump is running there is a lot of water running out the backwash line.

The o-rings look good, but I think that is my next thing to try and replace.

Does this sound like a reasonable thing to do, or am I way off base here?

I think you have a good handle on the problem and agree with your diagnosis and solution. Not familiar with those valves but don't think there can be another source of the leak. All the symptoms point to that. Multi-ports do the same thing when the gasket goes bad. That problem I have had.
Good Luck.
Al

Thanks! This weekend it should be warm enough to go out and try to replace them.