i just bought a 125gal tank, it came with a eheim 2017 filter, found out that they quit making these in the 80s, surprisingly the filter still works fine, but this filter has a 2 piece impeller shaft, anyone know why these filters have a 2 piece impeller shaft? also dose anyone know if i can use a solid shaft to replace the 2 piece shaft? i know that the eheim 2217 is basically the same filter, i guess the replacement for the 2017, i have read that the impeller from the 2217 dosnt fit the 2017 but i wonder if the shaft will work? any help would be great. thanks