Hey, guys, Y'all seem to know what you're talking about, so here goes. My Ridgid K-380 drain cleaner currently has 75 feet of 3/8 inner-core cable. It was shipped with 4 interchangeable cutter heads (spade, double blade, bulb and something else...) I used them for several jobs, and had acceptable results. I only use this machine for lines up to 3", and usually through roof vents and cleanouts (although sometimes through trap adapters.) Many times I have to run floor drains, so I must negotiate a trap. I had almost given up with this machines' cutter heads, as I couldn't successfully get through a 2" trap with any head. I have since removed all evidence of the interchangeable system, and kinked the end of the cable, as plumbers and draincleaners have been doing since the dawn of time. I have practically doubled the efficiency of this machine in doing so!!! So my question is...why offer these heads as a feature at all? Was I mis-using them? By the way, I am a plumber/drain cleaner (service) by profession, and have been doing so for many(9) years. what gives?