Who can I trust to repair my Cobra 148GTL-DX radio with added frequencies. It has not been in service for over 20 years. That was when I sent it out to a supposed COBRA AUTHORIZED repair shop (can't remember exactly but somewhere in the San Fernando Valley). It went out with a blown final and came back non-operational. I since then shelved it but now I miss it and want to use it again. The rig will power up, does not seem to receive and transmitting with any RF gain will cause squealing in the speaker.