My 1971 Spit side glass was only wedged into a thin rubber sleeve, sitting in the metal trough of the window regulator. It was the same on my TR4s. I left the window up, door closed, then carefully pulled up on the glass & 'wiggling' it to free it. Once it came loose on one end, and with the inside panel off, I used a wooden stick to pry it up & free. Installation was easy, put it in and press down.
Hope it works out for you. Dono