If you are shotgunning, randomly replacing things you are just gambling with guesses. The best way to repair the failure is to check signals, troubleshoot to locate the problem. Easiest to do this with an oscilloscope or logic probe, but I can do it with a DMM as well just looking at voltages. You have identical circuits driving each solenoid output that helps with comparing each section.

Don't forget that if you are talking about the special solenoids (pops and slings) these can be activated directly by a playfield switch. In Inkochnitos diagram above, you'd need to check the state of the switch solenoid 6 trigger and make sure IC7 pin 9 isn't seeing a stuck closed switch (active low)

You cannot cut a diode off in a switch matrix. You will confuse the switch matrix and a lot if bad things will happen.

Figured that was what you meant after the post. It's all good.

Many technicians are taught to approach triage situations using the “shotgun” method—replace all major components that usually are the source of machine problems. This is the most expensive way to repair a machine, and it doesn’t always work. Troubleshooting by testing signals with a DMM, oscilloscope, or lohic probe and understanding the function of these components and how the machine is supposed to work will get you there faster and more efficiently.

Theres only so much you can do without the tools or skills. Good luck.

Perfect...then use the DMM to check the pulse train instead of shotgunning. I don't own a logic probe and use the o'scope little in pinball except for audio troubles. I'd rather not drag out a lot of stuff, so mostly I use my DMM to see what is going on. Put the game in solenoid test, put the DMM in DC volts, and look for a positive or negative stuck signal or a pulse jump negative or positive. Works pretty well. Then start somewhere in the middle of the drive circuit looking for that pulse, comparing to an adjacent drive circuit for reference. Saves a lot of time and money.

I'd start at the 7408 comparing input pins 9 & 10 of the problem channel to a working adjacent channel, such as pins 12 & 13, and the output pin of the problem channel pin 8 to output pin of the working channel pin 11. This would give me an idea of what is going on and which direction to look to next.
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Quite possible...did you get there by test or by guess? Another thing is to use your sense of touch, is the PIA significantly warmer than it should be? Sometimes they get discolored when overheated for a time, like a big hazy circle on top.