Since the topic of fixing a bent dewshield came back many times, and the proposed methods seemed to me quite invasive and risky, I would like to share my own way of dealing with this problem. In my opinion, it is relatively safe and does not require any special tools.
The dewshield of the Towa 60/900 refractor was bent quite badly in several places. I used the method of manually pushing out the flattened fragments from the inside and pressing too sharp arches from the outside. I covered the pressed surfaces with 3 layers of masking tape. It is worth marking on it with a pencil the center of the distortion that we want to remove. Then, with a piece of wood on the outside and an old metal pump on the inside, I was compressing the area around the center of distortion using a rolling or swinging motion.
In case of pressure from the inside, I placed the dew shield on the edge of the table. The degree of its extension and the angle at which the tube is held allow quite a precise regulation of the pressure effects. What you cannot see in the photos is the other hand that I was holding the phone with. While working, I tried to use it to squeeze the dewshield so as to counter, in a sense, the side forces pushing the tube sideways.
Edited by LukaszLu, 27 March 2021 - 07:53 PM.