I have a second laptop charger, the numbers on it read,
19v DC 3.1A
Would that replace the original, faulty one which reads,
19v DC 3.42A max?
I am assuming it would still charge the battery, albeit a tad slower, (lower current output)
Or is there something more to it?

Plug it in and try it. It should be fine.

Assuming that the polarity and size of the plug match your laptop socket, it should be fine.

SD

Assuming the connectors are the same, the charger will almost certainly be fine. The old one is a 65-watt unit, the new one is a 60-watt unit. The old one is a slightly odd rating. You may be able to reassure yourself by scouring the labels for anything that looks slightly similar to "ADP-60".

Thanks, will give it a try.