i found this

[vinper]

Dema model 257 , not made any more but works , need a new squeeze tube assembly were acan I get it?

 

[Casey]

Hmmmm. So not sure but hopefully someone can help you!

Hope you're enjoying TFP Vinper!

 

[woodyp]

If you just need the tube, try Us Waterways. That could either be 1/4 od or 3/8 od. Or google stenner pumps for the black tubing.