Quoted from StratDoc:Below the bad SCR are through holes. I read another post that said those were for replacements. What type SCR do I need? The surface mount is CR088 but that does not bring anything up when I google it.
Can stick a logic probe no the gate of the SCR to make sure the decoder chip is doing work.
i think the alltek board has a through holes as well as surface mount pads, so you should be able to fit a new through hole SCR like MCR100 / 2n45064. The bigger SCR is MCR106.
Depending on the surface mount package type of the original SCR you can usually get a solder blob on all the legs with a traditional iron to get it loose. Cut off any / all legs if you can get snips on it. If the original SCR failed completely open you could probably even leave it in place, but I imagine you want it off.