a 'prybar' that you use for removing 16d nails sounds like it would cause damage. But a thin piece of metal or even a plastic shim would do the job... thats all I meant.

there is no 'lock', really, but the mechanism that forces the panel up as the cable moves it forward acts as one. This is why you must push the rear of the panel down as you push it back towards the trunk.

I will be the first to admit that it is not easy to slide the 25 year old roof back manually after it has been stuck.

Ultimately, the reason your roof failed is primarily due to poor lubrication on the sliding surfaces. Sure, the motor can take the stress, but the cable and its connection wear out quickly when they have to oppose all that friction.