So, been stupidly busy but decided this morning was the time to get this stat replaced.
...only to discover I don't have a 12mm allen key to remove the rad plug.

So, pending the purchase/delivery of one, I want to check everything else before hand. I've searched the forum but there are so many different posts about it it's difficult to see correct answers and I want to sanity check things:
1) I'm not losing coolant; level is fine and doesn't drop.
1a) No issue with matrix o-rings.
2) Top hose gets 'warm' but not hot after running (can be idle for a while or a drive; yesterday was a 10 mile drive on A1 at about 50mph)
3) The temp gauge barely gets in to the blue - will sometimes get half way in to the blue but wont go further - type of driving doesn't affect it (very slow cruising, up hill, down hill, foot down, etc)
4) I get slightly warm air through the vents even when set on BURNME.
This issue only started last year when I replaced the o-rings, something I've done before without issue. I haven't really driven the car for over a year though have recently had it stripped inside to fix various bits n bobs.
I have the replacement stat (2 actually; britpart is **** and doesn't seal, Bearmach seals well and opens well) to go in pending tool acquisition.
- how do you check the stat in place to make sure it's operating correctly? I'd like to check the current one and the new one once installed.
- There's no gargling anywhere and I've bled the system previously (due to leaks) to know that I don't have an air-lock (using the correct method in RAVE).
- Best way to check/test the temp sensor; could this be the cultprit?
Frustrated at lack of toolage and wasted morning time!