On Thursday, May 25, 2017 at 2:45:28 PM UTC-4, dpb wrote:
On 05/25/2017 11:36 AM, trader_4 wrote:
...

Update. I hooked up the air compressor and blew it out, going from
the shower head pipe to the tub and then to one sink. Blew out both
the hot and cold sides. Some dirty looking water did come out,
but no sign of any debris. Good news though is the flow rate is
at least double. ...

Probably scale/rust/sediment that at least is temporarily relocated if
not removed. If could manage to backflush _might_ do some good.

I've no klew on the specific fitting; don't recall ever heard the name
before even...

--

It's Hansgrohe. I called it Grohe, thought it was Hans Grohe.
It's a German line. I have them in the master bath, had it in
the kitchen too. They performed fine, no real complaints. But
like I said, the fancy designer handles just press on the stems.
I've never had to take one off, but don't expect I'd be able to
either at this late date. Not only are they probably stuck on
real good, there is no way to apply the pulling force. It's not
like a gear, where you can use a puller.