Stubborn American Standard shower valve leak

[Azure]

I’m pretty much at my wits end. I renovated my shower and used a new rough in single handle shower valve from American Standard. The shower (head removed from arm for troubleshooting) drips at a rate of 1 drop every 2 seconds. Where this gets difficult is I have replaced the cartridge 3 times and the pressure balance valve twice. All of these parts are AS parts and the last cartridge was pressure tested by AS before they sent it to me. None of these parts have made any change in the leak. I’m beginning to think that the housing is bad but it’s new so what could be bad? Has anyone encountered this before? I’m at a point where I’m thinking of replacing the entire valve assembly but this will require breaking into the tile which makes me sick. Looking into the valve body with a flashlight doesn't reveal any damage or really anything that seems a concern.

Any ideas?

Thanks,

[hj]

There are MANY places in the valve body which could have casting flaws and there is no way you will ever find them by using a flashlight. Where did you buy the valve, at a "big box store". If so now you know why plumbers NEVER buy their faucets there.

[Azure]

I bought the valve at a local plumbing supply store.

[cacher_chick]

A scratch in the sealing surface of the valve body can be enough to cause it to leak. Also, if it was sweated in with too much heat, it would be possible to damage the body that way.

Instead of tearing out tile, you might look at the feasibility of accessing it from the opposite side of the wall.