I have an AS-2518-23 lamp driver exhibiting some strange symptoms that appear to be tied to a small group of scr's, but I am beginning to wonder if it is actually a decoder chip issue. I do not have the means to test the decoder chip, and a test of the specific scr's seems to indicate that they are close to spec, and they do have very similar readings to surrounding ones on the same board.

Basically when one specific controlled lamp is activated Q30, a few other ones appear to be directly affected by it. The affected ones include Q1, Q2, Q4 and Q7. When this occurs, these four lamps turn on solid and/or flicker. This symptom is also present in attract mode as many of the controlled lamps turn on at that point, however what is even weirder is that the one controlled by Q30 does not turn on during attract mode, and it does not appear that it is supposed to.

So would this likely an scr, connector or decoder chip in most likelihood?