While I'm not familiar with a SA-RT30 I am familiar with other Panasonic DVD recorders.
You mention a "strange noise."
If that noise is "clunking" or "chugging" the most likely problem may be a dirty or failed lens assembly. The noises come from the lens assembly running up and down the rods hitting the stops in a failed attempt to read the DVD.
Other less likely problems are ribbon cables that are not making good contacts with their connectors or a failed Digital PCB (the "brains" of a Panasonic DVD recorder).