Rear rails can be hard to find it took me many months, but those need replacing. I eventually got some from the US about 3 years ago at a reasonable price, I'll try and remember where from, the guy breaks & sells Pacemaker graphics for parts.
When you change them it's important to get the shims right so the rails slide back smoothly. The screws are accessed from the base of the camera and it is possible to change the rails without removing the bellows.
Graflex.org is a great site but has a no trade/advertising for sale or wanted policy.
Ian