Keith,
I never yanked an Exploder tube, but if it's like the other 10 engines I've rebuilt, it is just pressed into the hole in the block. Removal would be: gripping it with vice grips, carefully if you intend to reinstall it. Then I apply a little Permatex on the tube before I install it, pressing it into the hole again! Just align it in thte same direction as before!
Good Luck!
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"Don't go where the road don't go." -Ringo Starr
Wil - '92 EB