I have an older PFC (Precision Flight Controls) Hardware all serial; yoke, rudder, throttle quadrant. The yoke and rudder are connected to the throttle quadrant via serial, and the throttle quadrant is connected to my laptop via serial to USB cable. I am running it on Windows 10 and xplane11. I do not have a serial port in my gaming laptop thats why i have to use a serial to usb cable. Windows detects it in device manager. I use serial test tool software provided by PFC; all controls are a mess, they move by itself. I opened xplane11 and try to calibrate it under Joystick/ PFC Hardware option, Its connected to the correct com port, but still all controls move by itself, fluctuates, jitters. Although i can still fly it, i just have to compensate on the unusual movements of all the controls. I also need to assign ATC on a button on the yoke, but seems like PFC hardware is limited on button assignment since i cant see an option to do that.

I do not have a protocol switch and the Elite (UCI) Universal Control Interface box.

I am planning on converting everything to USB, hoping thats can fix the problem. So what board should i get from leo bodnar or arduino? Or maybe a better serial to USB from leo bodnar should work? Or just a serial calibration software?

what i tried so far:
Different serial to usb cables that are high end:*edgeport, thunderlinx, io-gear, cable matters, and some generics.

opened the yoke and throttle quadrant for the first time, to check if there are loose wires that needs to be soldered, or even look for dirt. But everything inside is clean and untouched, wires are attached properly.*
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The jittering and fluctuating movement of controls was less before when i used PFC on an older computer thats also connected via serial to usb.
Ever since when I upgraded to newer laptop; the jittering became stronger than the previous computer.