Using FM transmitter with 5V USB power supply?

Unfortunately my old faithful Satechi FM transmitter got stuck in the work van aux power socket and in pulling it out the plug end detached from the transmitter end.

I want to have a go at repairing it by re-soldering the power leads but was wondering if it was possible to wire a USB power lead to it instead so I could use it with a USB power supply rather than rely on the work van aux power supply (not all the vans have them working).

The power plug has some electronic gubbins built in which I was wondering was a step down from 12V to 5V. I suppose I could test that plug with a voltmeter but but was hoping for some experienced advice before going ahead.

All said and done it is not the end of world as only one of our regular fleet of vans does not have an aux audio in to the radio and I do have portable speaker I can use instead which is just about loud enough in a wind-blown cab with the windows down in hot weather (no air-con).