Here's the pinout for that ballast tube. You can test it with an ohmmeter. The Sencore CR70 lists settings for the 7JP4 in the manual so it definitely supports it. You can even see the screen glow a bit while testing it.
Of course, you can also test one by popping it into a working set. That's quite easy to do by disconnecting the CRT socket and flipping it over to connect to the test CRT outside of the cabinet.
Ballast# 17A485459
A = 37 ohms
B = 132 ohms
C = 200 ohms
D = 111 ohms