A very belated update to this thread as work has been absolutely manic for the last couple of weeks (and weekends). Here's the home made anti-stall testing kit in action on the fuel pump:
It turned out that a slight adjustment was indeed required so it was worth checking. Ten points to Graham for pointing me in the right direction.
Now it's onto other more fun items on the to-do list like central locking trigger switch and custom door lock stalks...