Oh, I definitely feel your pain
Jackie. I use Carb Othello, Derwent, Conte, and Kooh-i-noor (spelling?). I use different sharpeners for different pencils, crazy

, I know.
I use this one for Carb Othello and Kooh-i-noor (I like it because it has replaceable blades), and
this one for Derwent and Conte. The large one can be used for all four brands, and sometimes I do that as well. The smaller one can only be used for the thinner pencils. No matter what, it is a real pain when they break, I think the entire inside shaft of the pencils is already broken when problems like you're having arise. Carb Othellos seem to be the biggest problem for me, the Kooh-i-noors are turning into a real favorite of mine, no breakage at all yet. I like Conte and Derwent, the Conte don't seem to break, the Derwent do, but not as much as the Carb Othello. But, I like the colors of Carb Othello................, so I just use 'em all and sharpen away! I much prefer the sticks also, but for commission work I do use the pencils in portraits for control. I find I'm not as loose as I am when I paint for myself.
I've heard about the microwave thing
John, not sure if it works for pastel pencils, but it sure is worth a try.
I'd also be interested in trying the Dahle 155 you mention
Merethe. That may be worth a try also, one cannot have too many pastel pencil sharpeners, especially with this kind of "history".