"No tool measurement! Please take care of the entry in the tool table."

I made the suggested changes, but unfortunately I am still receiving the same error message when I try to do a tool change.

I replied to this 2 days ago but I guess it didn't go through for some reason, very sorry about the delay.

I did try with the suggested edits but I had no change in behavior.

It wasn't something that I really expected to work, but I thought that it was worth a try.

I have just noticed that your INI file might not be referencing the postgui HAL file.
(Though I don't think that this is necessarily the problem)

Do you have a file "postgui_call_list.hal" in your config?

Yes, I do have the postgui_call_list.hal in my config, but all that it does is source the custom_postgui.hal file. I honestly don't know why this is there, I expect it was just listed in some tutorial and I followed it at the time.

Sorry, but I am out of ideas at this point. I have no experience with Gmoccapy.

Maybe try creating a new config from scratch (you can leave the existing one untouched and partially working, so you don't lose anything) and follow the instructions from the beginning again.