Rear Bottom Tailgate will not shut

Help is needed on my 2004,3.0 Vogue.
The old girl has been sitting in the garage since Dec.
Today I had to open the upper and lower tailgate to put some junk in the boot.
Tried to close the lower half and oops nothing it will not lock into place.
I've pushed the button on the lower half and can here the motor operating but it won't lock shut. I've had to shut the top half as to keep it in position. I've tried activating the central locking on the key and inside the vehicle, all doors and tailgate upper unlocking & locking, as soon as I lift upper half bottom drops down.
I will not lock shut. Battery is fully charged, been on a smart charger whilst not used. Any ideas folks what this could be. I do remember this happening last year but after a few presses on the lwr tailgate button I got it closed.

check the latches on the lower door.
when you press the button, they should move if not, clean and lubricate.
one of mine did it the other day..

good luck..

donp38 said:

check the latches on the lower door.
when you press the button, they should move if not, clean and lubricate.
one of mine did it the other day..

good luck..

Click to expand...

Thanks Don, yep just lubricated and all good. there are 2 black plastic parts that move back and forward, don't know what these do but they were sticking. I have lubricated them both and as I moved them back & forward I heard the motor activate.
Thank you for your help.