If I remember correctly (had a 162) Garmin used coaxial cable on those antennas.
Don’t remember the connector being all that much bigger than the cable itself. Why not pull and reroute?
Splicing a coax isn’t complicated, but it has to be done correctly. Guessing someone makes an in-line splice kit by now given the market size of cable tv
A lot cleaner to dissemble the antenna, remove the cable from its termination points inside the antenna, cut then resolder connections
The bigger issue is the fact that the unit and antenna have been NLA going on 20 years. Going to have a hard time finding a new antenna if this one gets messed up