1996 Ford Explorer Odometer and Trip Odometer

Each time I fill up my tank with gas, I reset my trip odometer. I gives me an idea of how many miles per tank I am getting. The last time I filled up, I noticed that the trip odometer had stopped at 76.1 and that the odometer had also stopped. I tried resetting the trip odometer back to 0 and jiggling the knob to see if it was loose. Anyway, neither are working. Everything else in the instrument cluster is working, i.E the speedomter, fuel guage, tachometer, battery charge, fuel temperature and engine temperature. I looked in my manual for a fuse to replace or somethig to tell me what might be the problem and couldn't find anything referring to this situation. The car is, as shown above, a 1996 Ford Explorer Sport, 2 wheel drive, 4.0 6cyl, 2 door with 1333381.1 miles on it. I have also had all the regular scheduled maintenance done as required in the manual and have all the paperwork for that. I had never had any problems with this car and REALLY like it. The newer ones are not made as well. Ford and my regular mechanic say that I need a new "instrument cluster" costing no less than $600.00 (maybe more) installed. If this is true, should I try to find one at a car salvage or junk yard instead of ordering a completely new one (if I can even get one - according to one mechanic, it might be hard to find on a 14 year old car). Any suggestions, help, instructions, direction would be so greatly appreaciated as I don't have $600.00 or more and would have to put it on a credit card, which I would hate to have to do. Thanks so much for your time, consideration and any information you might be able to share.