Transistors can look good but test bad. I'd grab a multi-meter and set it to diode test. Check across the legs of the transistor. Reading should be in the 0.4-0.7 range. A dead short or no reading can indicate a problem. Check that transistor value and compare it to the other ones just like it. If it varies at all, might be bad.

There are great video tutorials on YouTube about how to check a transistor.

Since you're not skilled in pin repair. I'd suggest subscribing and watching the YouTube channel 'Joe's Classic Video Games'. They do a lot of pin repair series and they explain everything in simple terms and show you a lot of tips. Great information on their channel.

Another thing your issue could be is a wire possibly pulled loose from the white plastic connector on the circuit board. The IDC connectors can be troublesome.