I am a hobbyist and a general fixer around the house. I know just enough electronics to get into trouble. I have an old inline cord lamp dimmer with switch that stopped dimming. It only turned full on or off. In reading online I gathered that the triac was likely ruined by a power surge. The original triac was X25783. I thought that as long as the ratings exceeded the requirements, I could use anything. I purchased a BTA16-600B, soldered it as the previous had been and tried it. Now the pot travels nearly the entire way until the very end where it lights completely and only limited dimming is possible by slightly backing off. How did I screw up? Thanks very much.