Honda bf75a 75 hp weak telltale and overheat

good afternoon all
advice please ? honda 75 hp BF75A 1996 has a weak telltale and a red light on remote control for overheat!

i have taken the impeller out, its fine. taken the thermostat out and tested, its opening ok.
i just dont know what else it can be?????

there is another box on the water system below the thermostat housing which has three bolts, this houses a spring and a black valve type of
thing, cleaned this out and replaced but no better.

now the red light on the remote is coming on, which means overheating ?
engine does not appear very hot ?!!!!
running has been in a plastic barrel full of water so far, monday shes going to the water proper to investigate.

any advice please / any photos of info
thanks in advance
iain

Have you had a look at the temp sending unit to see what kind of shape the wire connection is in?

Alan Hicks said:

Have you had a look at the temp sending unit to see what kind of shape the wire connection is in?

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thanks for reply alan
all appears in good shape !