So the quad op-amp on my OPTi 82C929A to amplify the sound on its YMF262 has finally bit the dust, and I've looked through boxes upon boxes of broken game consoles and motherboards to try and find the same op-amp. I haven't found the exact same op-amp, an LF347, but I did find two equivalent quad op-amps: the BA10324AF and the LM324M. This is where the major problems come in: with either quad op-amp, at the mixer settings I typically use my 82C929A, I get a MASSIVE amount of distorted FM Synthesis unless I turn down the volume REALLY low to the point of being inaudible. It sounds horrible, let me tell you. It sounds like a mess of static, popping noises and heavily-distorted FM Synthesis. With the BA10324AF, the distortion was so bad I heard a massive mess of distorted FM Synthesis at high volumes and absolutely no FM Synthesis at really low volumes. With the LM324M, it's a different story. I can hear sound just fine at really low volumes, but as soon as I start increasing the volume of the FM Synthesis too much, it gets just as horribly distorted as with the BA10324AF. I've even tried placing multiple different resistors ranging from 15Kohms up to 750Kohms to reduce the volume of the audio coming off the YAC512, but to no avail. The sound is still horribly distorted no matter what resistors I place on the YAC512's outputs. So these are my questions for anyone who's good with electronics:

1) Where should I place the resistors? Between the YAC512's outputs and the LM324M's inputs, between the LM324M's outputs and the inputs on the rest of the audio amp or just before the FM Synthesis enters the Crystal CS4238?
2) What value should the resistors be?