CHIRP

I'm sure some work will be required to support the modded 8800, but I don't think that's actually your problem. It looks to me like the clone in stops immediately and never actually gets the radio image and fails the checksum calculation as a result. Does the radio proceed with the send procedure? Does chirp fail immediately once you push the button?

I solved the first problem, which was a PEBCAK error - Problem Exists Between Chair And Keyboard. I found another instance of Chirp running in the background. Once I closed all windows and verified only Chirp was running, I was successfully able to download from radio.

Attempts to upload to the radio fail due to the Radio Error: Radio did not ack block at 0
This appears to be a common problem with Yaesu radios. Here is the debug log:

[2023-10-30 21:25:26,471] chirp.wxui.clone - DEBUG: Prompt pre_upload disabled for radio
[2023-10-30 21:25:26,471] chirp.wxui.clone - DEBUG: Opening serial 'COM5' after upload prompt
[2023-10-30 21:25:26,564] chirp.wxui.clone - DEBUG: Serial opened: Serial(port='COM5', baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=0.25, xonxoff=False, rtscts=False, dsrdtr=False) (rts=True dtr=True)
[2023-10-30 21:25:26,730] chirp.wxui.clone - ERROR: Failed to clone: Radio did not ack block at 0
Traceback (most recent call last):
File "chirp\wxui\clone.py", line 69, in run
File "chirp\drivers\ft7800.py", line 338, in sync_out
File "chirp\drivers\ft7800.py", line 216, in _upload
chirp.errors.RadioError: Radio did not ack block at 0
[2023-10-30 21:25:32,427] chirp.wxui.clone - WARNING: Stopping clone thread

It's a "common problem with Yaesu radios" because they have the most brain-dead cloning protocol and don't really allow the PC to do any negotiation. Thus any upload failure results in that message because we can't get anything more useful from the radio. In your case, it's likely because of the different ID string due to your MARS mod. Please attach the image you downloaded and I'll have a look.

Thanks, but looking at that driver, it should actually be sending whatever ID string it got from your radio back to it during an upload. If you're doing the upload dance properly (i.e. starting chirp at the appropriate time for the radio being ready for it) then I'm not sure why it's not working. The driver works for me locally.

If you could describe in detail the steps you're doing as well as the exact behavior(s) of the radio at each step I might be able to spot something amiss.

Brilliant! The MARS/CAP mod reset the radio. From that point, I should have started with a new blank download for re-programming the channels. My mistake was to attempt using an .img file created prior to the mod. Those previous .img files are no longer recognized post-mod.

Thank you again for your patience and troubleshooting. This issue may be closed.