The spectrum analyzer 7L5 contains two 155-0035-00 quad op amps. One of the four was faulty. No direct replacement was available. Therefore, I disconnected the three affected pins, then piggy-backed a LM324 in place with ±15V lines attached to the 115-0035 and added three wires for the socket. The remaining three op amps in the LM324 are not used.
Works nicely. The gain/bandwidth product of the LM324 is much smaller, but that does not affect the performance.

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