"So please whats most likely to need fixing or replacing.

the tone pot, or the capacitor, or whatever other components ?"

Depending on the construction material of the capacitor (and I won't give a lengthy discussion here) - capacitors of the type used in that application tend to be robust and have a long life.

More likely is the variable pot (potentiometer). Usually the wiping contact that moves gets dirt under it, or some other problem. A squirt of the correct pot lubricating liquid (NOT WD40! - which is NOT a 'lubricating', but a 'cutting' oil) will usually bring it back. Otherwise a replacement may be called for.

If the sound is still getting thru, then while it may be a failed (dry) solder joint, then it will most likely be confined to the area of the capacitor and pot wiper arm connector.