Spark when key is turned to the off position?

There are 4 pins on the ballast. The two resistors are in the long direction. Place meter in Ohms. Place the two leads tips together, you should read 0 to 0.2 Ohms. This will verify the meter is working. Then place the lead tips terminals 1, 2 polarity does not matter on resistors. Read resistance, repeat for 3,4.
One resistor should be 5 Ohms, the other 0.5 to 1.5 Ohms.

1 xxxxxxxxxxxx 2

3 xxxxxxxxxxxx 4

If ballast is good, then time to follow suggestion of testing pickup resistance, and checking reluctor to pickup gap.