Sell the stupid thing and buy a Tomtom Rider 550. It updates over Wifi so you don't have to deal with adapters, cables and hubs.
Garmin should be ashamed of themselves for remaining so quiet on such a big flub. It's inexcusable that the solution, two years after it was first reported, is to spend an additional $50+ for another piece of hardware after shelling out $900 for a brick. Garmin should be offering to send a proper cable or an updated navi with a hardware fix to anyone that asks. If this were a car it would be recalled.
Things will only get worse for Garmin customers as Intel Macs age out and M1/2/X are the only Macs you can buy.
If I were more ambitious and less lazy I'd initiate a class action suit against them for knowingly selling defective hardware. I'm that angry about this.