Help! 1978 911sc Door lock driver side would NOT open from inside round knob
 

I need advice how to fix driver door lock for my 1978 911sc...

The door lock would not open from inside round rotation door knob but would open with inside pull-up lever handle...

The key would not work either from outside...

Any advice highly appreciated...

I would recommend pulling door card to inspect linkages.

when I bought my car the little pull up knob was missing, When I removed the card I found it down inside disconnected, put everything back together and all is well

I assume that your linkage from the round knob has come apart...this job is very easy to do only about 6 or so screws to remove door card and all the linkages are pretty straight forward

p.s. there is a plastic membrane that should be fixed to the door behind card I you remove it it should be put back, this is a vapor barrier

My round door knob linkage - just fine...

I may suspect the malfunction of the locker itself...!?

as if I turn/swing the side door assembly latch - round knob would function but as soon as I release outside lock lever handle - inside round knob would not work...

The key would not work either...!?