727 Not Engaging Gears

Are you saying the linkage is all hooked up and you can move the shifter?

If so, the adjuster might have loosened up. You need either two people, or look under in park, move to low, then look under again and see if the trans shift lever moved. If it did not.........adjuster is loose and sliding

If it did, the rooster comb came loose inside the trans from the shaft