Hi Mike,
you need one Prob for 1 Cylinder, always the closed ends to Upperside............You must break off the Pin and cut the spring with a very good forceps (is this the right word? I don't no) for Hardmetal.
I work in a company to built In-cirquit-testadapter, always when a Adapter come back to need new Pin's, the old Pin's go NOT in a dustbin, - they go with me in my Hobbyroom
On the Pic's you see the hiding-place from the Pushrod-arms

........ and Springs from the 0.40, 0.50, 0.75 and 100 inch Probes. The small pieces are 0.40 inch for my Dr.1 and E.V Rotary-Engine's, ca. 4mm long.
@Doug
Thanks, that's a very good Idea, i will download your Loz.
Servus
Bertl