Hope I have this question in the correct forum, I am new here.I have a 1991 z28 305 tpi 5 spd that the speedometer does not work, the speed sensor has been checked and is good, I see in the book that there is a speed sensor buffer located behind pass side off dash I cannot find it. also when the speedo was working it was about 10 mph fast, it has had a gear change, the drivin gear has 22 teeth what do I need to do to slow it down.Thank you in advance for your help.