Efke 25 is a unique film that you might enjoy. Efke and some other films require a water prewash to remove that anti-halation dye before developing. It does not harm any b&w film to prewash for 1 minute. I prewash all sheet film in the Yankee tank.

I do not think that the lack of prewashing would cause a gummy residue as you describe. I also suspect contamination in the reel or tank.