There is a product called Plastifix that I have used to repair bike plastic for years... It is basically uncured ABS and works great... It is used as a fridge liner repair product in the appliance industry. I have supplied a few of my friends with this stuff as the need came up.

 

how do i find this stuff? i have a couple very small cracks in the plastic from age and don't waunt them to spread.

 

Reliable Parts or Amre Supply both carry it under the part number PF041. It comes in white and almond colours