I'm not sure if this applies to INTV, But my old TI-99 had a white noise generator as one of the sound channels. They made for pretty good generic explosion SFX.
Try putting Dawn or other dish soap on the disc, both sides. Don't be afraid to be generous with it! Scrub the soap covered disc with your fingers gently, then rinse off the soap and dry it.
Baby don't hurt me, don't hurt me, no more!
Sorry couldn't resist. XB is Extended Basic. There should be a link to the manual in the Development Resouces thread.