tranny is having trouble shifting into 2nd (AT)

i just recently bought an '83 240 DL and it was working fine the first day, but on the second day when i shift into D, it doesn't seem to shift into 2nd gear. after fiddling around with it awhile, it worked but only after i shift into 1, then 2 then D. does anyone know what's wrong with the tranny? is it a major problem? can it be fixed by a beginner? any help would be greatly appreciated. thanks~