I wasn't aware of an "o'clock" positioning - Smithy could help clarify that - but wherever you put it, it should only poke out into the exhaust stream about 3 to 5 mm.

It may want to move around in and out a bit, depending how you've bent the thing up to get it into position - I just used a pea-sized drop of silicon sealant around the thermocouple wire just where it goes through the little hole on the outside of the exhaust nozzle to help hold it in place. The silicon breaks down under heat eventually, so I just clean it off and put a fresh lot on. I'd be interested to hear of any other suggestions...

BJ