Models need fixing

My friend has some models from the beta that need fixing so he can make sweps.
The models are:
Brickbait: Bottle
Brickbait: Cremator head
Brickbait: Headcrab
Beta Pistol
Manhack blade

What’s wrong with them?

They’re from the HL2 beta…
The beta ran on version 37 of the source engine and the retail is version 47 (I think).
So if you try and open them in any source game, it crashes.
but
You can open them with a modeling program and fix this somehow, I don’t know how its done because I’m not capable, thus this request.