
Suggest McQuires #1 plastic polish.  It will help somewhat but nothing 
will remove deep scratches without making it worse than it already is.
McQuires will do something for fine or light stuff.

Also suggest calling your local plastic shop.  In Calif. "TAP PLASTIC" is
a chain that carries most of what is needed for repair and sometimes
replacement of plastic bits.  Telephone in the Bay area is 415-962-8430.
I'm not sure how amenable they are to shipping.  I have found that they
have several excellent products for cleaning, and removing crap from
windscreens and face shields.  Also they have one called "lift-it" which
works real well in removing sticky stuffs such as adhessives from plastic
wihtout scratching same.

Luck,