Looking for a diagram for a shimano cardiff 400a

If you can't find with a search for st-ef40 diagram or on the Shimano site then it does not exist. Although not identical carefully disassembling the other shifter may give you enough insight.

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

Here is the PDF for the Cardiff 400A Reel:
http://fish.shimano-eu.com/media/fishing/techdocs/en/CDF400A_v1_m56577569830556013.pdf

http://techdocs.shimano.com/techdocs/index.jsp

Shimano only posts consumer-level documents.

http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/ST/EV-ST-M510-1899_v1_m56577569830609281.pdf

Elves build these things.

If this is not the diagram you are looking for, please check techdocs.shimano.com for the proper one.
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/CycleComputer/SI-0045A-001_v1_m56577569830684407.pdf

http://techdocs.shimano.com/techdocs/index.jsp

try here

Go to shimano.com and download instructions.

I figured it out by myself.

Please DON'T contact me again.

You can download an exploded diagram of the 7900 series STI shifters here:

http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/ST/EV-ST-7900-2874E_v1_m56577569830670749.pdf

You can reassemble them according to this diagram.