w126 monovalve identity (?) partsshop ?

[unkl300d]

My 1989 300SE has no heat (climate control works fine) and I suspect the monovalve.

Apparently there is an insert which can be replaced if the diaphram is ripped.I located what seems like the monovalve.
Facing the battery, to the right of it behind a firewall.
I see this silver color square plate with a small cylinder in the middle and a small harness plug.
Four screws hold the plate down.

If this is it, are there any precautions to take for removal?

I hope partsshop has the insert.

thanks

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