Ah, a piece of equipment labelled "Treck" - that is a blast from the past.
Treck started up as an employee buyout of the Canadian business of a former division of Eastman Kodak named Eastman Photographic Stores. They sold equipment mostly to commercial labs and professional and commercial photographers.
It may be that others in different markets will recognize that mixing valve with different branding.
And the person I would ask your question of is someone with knowledge about plumbing - people who install high end showers tend to know how to make them behave better.
It's actually a rebranded Leonard valve.
I have had two,used, mixing valves before it and they failed.
The costs to put repair kits into them was more than I could justify!
This ,Treck, one had a leaking vacuum break so I just discarded it.
At $25 CDN for the valve the plumbing parts cost more than the valve!
I had a Powers Photoguard mixing valve before which had way more sophisticated/complicated working parts which wavered from its setting and before that a Leedhal which also failed.
The costs of repair kits for all these valves is in the region of 50% of new cost which for the amateur tinkerer is too much.