Gear Shift problem

[HBlue]

I have a 76 Custome Deluxe with the 350 Automatic Trans.

What would cause the gear shift to not lock into place?

When I shift from Park to Drive, it does not go into gear.
I have to go to 2 or 1 for it to go into gear, then go back up to N and back down to Drive.

When I shift from D to R, I have to go nearly to P for it to go into reverse.

It just started this a couple of days ago. Is there some linkage I need to adjust.

thanks for your help.