I recommend servicing the chime unit (unsolder, remove from cabinet, disassemble, clean and polish, reassemble with new piece of foam under the chime plunger, resolder wires).

Not difficult to do and will make the chime unit look and sound like new.

Might want to also adjust the tightness of the nuts on each chime bar as that can affect the tone and duration of the sound. And also confirm that the tiny washers that sit between each chime bar and the body of the chime unit are in place. If not, you can buy new ones from PBR.

Hope that helps!