Just drill the lock if you don't have the key. Either put a new keyed lock in or a thumb lock.
Be careful cleaning the playfield as the reds will fade fast if you scrub too hard. I start with a simple wipe down with a blue shop paper towel sprayed with simple green. Everyone has their own technique. Do not wax the playfield until you're certain it is clean or you just seal in the dirt and grime.
The reproduction post that are supposed to be for these older machines have an odd blue hue to them. Also documented on pinside.
Some just change over to the new red post or clear if you want to light em up.
And http://www.pbresource.com/ is the place to become a customer.
-Mike