No high gear
 

My 62 tempest conv. All of the sudden is stuck in low ? Driving inthe afternoon all was fine. Went for an evening cruise and wouldn’t shift into second . It never has slipped and the fluid level is good , maybe a hum line to modulator went bad ? They are very old . At least that’s what I will check first. Just wondering what else it could be ?

Vacuum line is what I meant

Could be the modulator, governor, valve body issue or could be bad seals on the drive clutch. My 61 has the same issues. I have checked the first 2 items, all ok, now to pull the trans pan.