De-clicker effect question

First I made it louder …
RMS normalize to -18dB, then (soft) Limiter -3dB (no make-up gain).

Then I applied the notch filter code (above) to remove the constant whine.

( the code will work whether you make it louder or not: it’s not threshold dependent )

BTW there is a loud 10Hz signal on your original …

10Hz is inaudible, but could cause raspy effect if a tool which is threshold-dependent is applied.
The code above includes a high-pass filter which removes everything below 20Hz.
So you should apply the code before applying any other processing, (e.g. before de-click, gate, compressor ).