2006 997 C4S Driver Wiper arm loose not moving correctly

[bhaden57]

After driving in rain for maybe 45 minutes , wipers intermittent the drivers side wiper arm wouldn't sweep and barely moves a few inches and stalls out.
The arm is loose on the rotating post and can be moved easily by hand. No linkage parts seem damaged but the splined post looks like it extends higher than passenger side. Arm base doesn't cover it like it does on passenger side .
I ordered installed a drivers side front Wiper arm because that arm was not moving correctly ( only moves a few inches and then inteferes with passenger wiper ). Car is still not drivable because drivers wiper doesn't work.
The motor works , the base where the arm attaches spins but it doesn't move that wiper What to look for or try ?