Peugot 306. 1.9 D How to check stop solenoid is working ok?

Car is a V reg 1.9 non turbo, non HDI model.
It has been a poor starter and lumpy runner when cold for some time.
Car has Bosch fuel injection pump.
Yesterday morning it would not start. Engine span fine, no warning lights. Clean air filter, plenty of fuel.
Have fitted new glow plugs and checked that control relay is working ok.
Still will not start.
Next suspect is stop solenoid on the pump, which I hav n't found yet. There is a black 3 pin block connector feeding a cable that goes into the pump.
From other sites this may mean that there is an imobiliser link.
How can I check that the solenoid is working ?