Thank you. How much should a repair like that cost? or is this something I can do myselfI would be a little concerned about the location of the crack. I would guess that it is a reflection of the twisting and pulling forces applied to the transom. It is likely not a big deal as it is small and located in an area of minimal stress but I would certainly want to roplene weld it back together and watch it for any recurrence. Flex seal would likely be a waste of your time.
Just my 2 cents.