Just repaired my Band 2 strap with this stuff: https://www.mcnett.com/gearaid/tenacious-tape#10691
See the attached image. I'm very pleased with the result and can now use my Band 2 again. The tape is transparent, very strong, waterproof and sticks to rubber. I wrapped the tape right round the strap so that it also sticks to itself on the under side. I used a hairdryer to gently warm the tape to shrink it at the corners to fit the strap perfectly. Hope this helps someone!