I have a Mark 1 Thunderbolt Ignition Analyzer the type that fits in the black briefcase. I have had it since 1973 when I started working on Mercury Outboards. I have lost the instruction manual for it which is not good. Now after 30 some odd years I am once again working on Mercury Outboards for a Dealer that specializes in vintage Mercury Product. If anyone has a copy for the unit I will glady pay for it. Thanks for your help. Tom Carter Former Mercury Master Tech