[Closed] Technical question: How to service pedals

What with all the fun going on, i forgot that one of the reasons i joined this forum was to get advice on technical matters!

I have a few sets of old pedals, which are a bit to very rough in operation, that is, they don't spin freely on the axle. I notice some of them have a nut on the outside end, but it's recessed into the body, so inaccessible with a spanner. Are they like hub axles inside? I assume I'd need a socket set. If so, what size, or are they all different? I've normally just replaced pedals when they've worn out, as they're relatively cheap, but if they can be serviced at all, then they might be ok for spares and town bikes.