Had this happen today
I have a Honda CRV and flat tow behind my Berkshire - I use a Ready brute Elite tow bar with integral inertia brake. There is an aircraft cable that runs from the front baseplate to the brake peddle - this cable is in a sleeve.
While driving the car today I noticed it really slowed down when I took my foot off the gas peddle so I pulled into a shopping mall car park to investigate. After a little head scratching I realized that the brake peddle did not have a lot of movement and the cable to the baseplate was tight. I went to the front of the car and tugged on the cable and it did not budge.
Minus 20 C outside so concluded water must have gotten in between the cable and the sleeve and frozen thus holding the brake peddle down. I disconnected the cable from the brake peddle and the brakes released - problem solved.
Just sharing this in case any of our Northern members experience a similar experience.
Will ensure this gets attention when it warms up
2011 Berkshire 390RB (Front airbag upgrade & 275/80R tires)
2016 Ford Edge SEL 3.5ltr, Blue Ox baseplate, Ready Brute Elite tow bar, Brake Buddy Advantage Select