1978 chev wont shift into second gear, automatic

I just bought a 1978 chev pickup. It sounds like its going to shift into second gear, but wont.... It is an automatic transmission. What can I do?

I just bought a 1978 chev pickup. It sounds like its going to shift into second gear, but wont.... It is an automatic transmission. What can I do?
WHAT ENGINE AND TRANSMISSION AND TRUCK SISE AND 2-4W?
Fluid level and condition?

Check modjuator valve and tv cable and adjustment if it has on.
Also governor and gear.
Does it have good reverse?