As recently I started tinkering with ZX Spectrum hardware, tested one old joystick I had. Up and right positions did not work during the games. Tested port reading with one simple program:
10 LET x=IN 31
20 PRINT X
30 GOTO 10
There was no reading in up and right position.
I took apart joystick case and tested connection between PCB and plug – there was no connection for up and right wires.
So, just took now DB9 female connector and soldered it instead of an old one that I have just cut away.