I may have placed mine in the wrong spot. What tape or other adhesive do I need to redo it?

The adhesive used to put badges on cars is very strong and could possibly work. Water doesn’t seem to bother it

I found this in TW comments section:

 

Comments:I've had one for 5 years now and can attest that it works great. Definitely makes a difference if you fish in and around aquatic vegetation. Mine has performed incredibly well clearing my tm prop of primerose, hyacinth and elodea on the CA Delta. **Don't use the two-sided tape that comes with it though, it will fail. I researched it and used Devcon waterproof "2-ton" clear epoxy and it has stayed solid.

 

I've seen the 3M two sided tape at Auto Zone.

 

Good Luck,

FM

Reach out to Steve (ninja grass blade)  he'll help you out.