RS232 punch out not working

I'm after some help and advice regarding an RS232 problem.

Machine is a vertical milling machine Shizuoka B-3V with Fanuc 6M control.

RS232 has been working fine with no issues for years using the same hardware/cables/pc

The issue is the machine control is able to receive programs from the desktop PC but is unable to punch to the desktop PC

Machine motherboard is A16B-1000-0030/04C
ROM board is A16-B-1200-0150/01A
Graph Int./Punch board is A16B-1200-0310/02A
BMU board is A87L-0001-0084/05B

From reading the forum it looks like there may be a problem with the RS232 line receiving chip SN75189. Does this sound about right? Is this chip located on the A16B-1000-0030/04C motherboard or the A16B-1200-0310/02A Graph Int./Punch board? Assuming this chip is the issue I'd look to send the offending board away to get a new chip fitted.

Before I pull any boards from the machine I'd like some advice as to any procedures I should carry out first. Would I loss any programs/parameter settings by pulling the boards as I'm unable to punch out any of these at the moment. Once the RS232 receiving chip has been fitted will the board need anything else doing to it before fitting back into the machine?

Any clarification needed please ask.

Looking forward to receiving some help/advice so thanks in advance.

Just to update, in the above I should've said the line sending chip SN75188 was the likely culprit.

Anyway, I've been playing around with an RS232 mini tester so does this help anyone confirm where my problem is?

Picture1 shows the mini tester connected to our cable leading to our PC
Picture2 shows the mini tester connected to the machine only
Picture3 shows the mini tester connected to both the machine and the cable leading to our PC with the control in EDIT mode waiting for program to be sent
Picture4 shows the mini tester lights during program being sent to the PC

So I've managed to get the machine to punch programs now. I changed the A16B-1200-0310/02A board. I'm going to send the old board away and get the output data chip changed so that I'll have a spare board if I ever need it.

Now that I'm able to punch from the machine I thought I'd get a parameter back up. I've managed to punch the parameters from 000 to 0731 using P-9999 but parameters 1000 to 3127 have not been punched. Can anyone offer any advice as to why these other parameters are not punching?