If you are using light pens you may sometimes think your pen is going bad when it is really the CRT screen. These screens will still be readable to us humans but the pen is struggling to read it's signal.
You can use Touch Screens on your existing RapidFire system. You can do this one station at a time or with the whole system. The Touch Screens are widely available on the web for $400-$500 for Elo Touch 1515L Accutouch 15" Screens, and 17" screens are only about $100 more. I can teach your technician how to do this so you may upgrade the stations at your leisure.
The RapidFire Point of Sale system was designed to allow the #2 computer to become the #1 computer in the event of a software or hardware failure on the #1. There are intended to be nightly copies of some files from the #1 to the #2 computer. This basically works except that as is discussed in the SafeGuard tip corruption on the #1 can propagate to the #2 and then you have a big problem. Plus in the event of a catastrophe like a fire your customer list could be gone forever. DOS backup routines to tape drive or zip drives were not made available by the RapidFire Vendors but have always been available. One thing you can do today is use a product like Fastlynx , http://sewelldirect.com/fastLynx3.aspx , and through a serial port, while all computers are out in DOS, you can backup your #1 computer to a Windows PC on a regular basis and then you can burn this to a cd or save to a file server etc off site and you are protected better. I don't recommend using the #1 parallel port for a backup as that is where your software key is and I recommend that the software key is touched as little as possible.