Hey Jeffrey,

My Tiico inline-4 has the same dipstick tube setup.  It is a press fit, or in
my case a hammer fit.  I recently replaced mine, so here is what I know.  The
tube goes down a half a foot or more into the block.  At the top of that
part, where the flange meets the block, there are a half dozen ridges that
compress when they enter the block (they look like threads to the untrained
eye).  To get mine in all the way, I used a chunk of angle iron and hammered
it in, rotating the angle iron around the flange to evenly seat it.  It
works.

Aside from getting a new dipstick tube, you can try wiggling the tube out a
bit, twisting and pulling up on it.  Be careful not to bend it.  From there
you can clean it up and maybe put some sensor-safe RTV sealer on it and push
it back in.  Or, try a rubber o-ring.

Hope that helps.

Bill Marshall
85 GL Tiico "Pandora's Box"
Aurora, IL