Recently acquired a tired old DX-40 with keying issues. Slight frequency change after key-down ( chirp ), now sometimes will not stop oscillator on key up. I'm suspecting the 0.02 bypass caps ( C4, 10, and 44 ) on the keying line, but can't imagine a failure mode that would be intermittent for these disc ceramics. Advice? 73, Curt KB5JO