If those were mine, ’d drop an email to Grabow from their website and see what they charge. especially if these hold a sentimental value to you. To get the Grabows with metal pieces back in smoking order, that’s your best option.
An alternative for nonmetal ones is too look up forever stems and see if they fit. You’ll need to take some measurements. Walker Briar Works used to make them, but the owner retired in 2020. (I have two for my cobs… very nice.) I see Vermont Freehand sells some too. If you are handy you could order some stem blanks from Vermont Freehand and try your hand at shaping your own stems.
Link to Vermont Freehand:
https://vermontfreehand.com/product/...stem-filtered/