Consider this.
I had this actually happen to me.
I was performing a private pilot check ride in and ASK 21. When it came time time to release, the release mechanism jammed and failed to release.
No radio was installed at the time.
We initiated the glider can not release signal. The tow pilot assumed this was a simulated situation since we were conducting a flight test.
After repeating the maneuver several times the tow pilot assumed we should land on tow instead of cutting the rope!
The PA 25 tow plane has a retractable tow rope.
We made a successful landing and I wheeled the ASK 21 to the shop and installed a radio! And fixed the tow release.
Rex