Hi I found out how to fix this problem, so what you do is you take an O-Ring and you put it on the second Ridge of the upper black part where the dipstick top is located. It seals it shut. Worked on my 02 civic

 

My 1996 DX auto transmission dip stick was loose when I first got the car about 10 yrs ago. I tried the o-ring trick but not with much success. I replaced the dip stick with a genuine Honda part and it fit nice and tight. Now it is loose again, but not quite as loose as before.

 

The rubber that sits on the top of the dipstick deteriorates over time, reinforce it with some duct tape, an o-ring or a small washer.

Or just be resigned to buying a new dipstick every 6-10 years.

 

i just fixed my today with a simple gromit from advance auto.. Now its in there snug

 

Easiest and best fix is a new dipstick from Honda. It seems the rubber seal that's on there shrinks and deteriorates over time. A rubber band or an O-ring could lead to bigger problems if a piece of one of them finds its way into your tranny.
Duane