I just picked up a 99 china cobra ltd st. Tx works on all channels, but no Rx on channels 1-19. Any help pointing me in the right direction would be greatly appreciated.

Somebody tampered with internal adjustors seems to me. you can take a screw driver and turn off receive for so many channels but crank it for higher band. It was probably locked on a upper channel for a Friendly chat station say Channel #28. Where they stayed and talked on 1 channel all time. Could be that. Maybe its got broke wires or board on that other set of channels or parts fried, chip bad etc. Get it checked out at CB shop. if you have any knowledge, turn IF to receive and crank up receive inside radio. If don't know anything take to shop..sounds like simple fix to me.