Im having hard/no upshift issues on my '99 Hyundai accent, 76k miles Auto-transmission. Out out the blue the revers gear goes out and trouble with 1-2, 2-3... Shifts, I've dealt with this issue a month before and replaced trans. to solve the issue that once again manifested itself. I have disassembled original trans. to find no mechanical issues and everything in great condition. Just purchased control solenoid in hopes of solving permanently but would like advice on diag. Techniques with MS906. Thanks