Replace it with a Hasselblad prism or chimney finder.

Also, there are diopter elements available for the magnifying glass in the Rolleiflex hoods. I ended up with one in a used Rolleicord I bought. I had no idea it wasn't standard, but then I noticed the subtle '+3' molded into the rim. Man, that made all the difference. I've communicated with Harry Fleenor at Oceanside and he has some in stock. I have no idea how to determine the proper strength- I use around a +2.5-3 reading glass strength, so the +3 makes sense. Then again, in a Fuji GW690 rangefinder I used a +1 (Nikon FM series diopter) and it worked well.