I recently changed the 3 speed 4 wire switch on a ceiling fan as the old one had a broken collar. I purchased a replacement at Lowe's. The replacement worked at high speed only. I was careful in noting which color wires went into slots 1,2, 3 & L. Thinking that the new switch was defective, I purchased another at a local hardware store with the same results. I re-installed the old switch with the broken collar, and the fan operates on all 3 speeds. However, I still need to replace the switch. I read something on your site about " normally open " and " normally closed" switches. How does one tell a normally open switch from a normally closed one? and where would I purchase the switch that I need?