4KS broken dipstick housing

[nicholls@mikey.convex.com (Sam Nicholls)]

I'm not sure about the proper terminology, but here is my best
description of the problem.  This is an '86 4000S 1.8 liter.

The oil dipstick tube, which holds the dipstick, has a red plastic
shroud at the top which mates with a similar red plastic shroud
near the handle of the dipstick.  Well, the shroud on the tube
has broken off.  So the dipstick just sits in the tube without
forming a seal.  I'm concerned about water and dirt going into
the tube.

My question is, how do I fix this?  Do I replace the dipstick tube?
How does it attach to the block?  Has anyone concocted a 'homemade'
remedy?

As usual, any advice will be greatly appreciated.
-- 
Sam Nicholls <nicholls@convex.hp.com>
'86 4000