Replacing old cases

Diff strap for the Sekonda and a light buffing of the case and nothing else. 

Leave the Timex alone as well.

Do whatever to the others

Cheers matey 👍 I will take that on board

The cases appear to be in fine shape? Strap, do what you want; they're surely not original anyway. At least one warrants a new crystal. Otherwise I wouldn't start frankenwatching these. If you don't like them, pass them along to someone who does.

It is your watch so you can do what you want with it.  Somone already said refurbish and change the strap, that is what I would recommend.

Yes there original, defo thinking about franken them.

Ok. I on the fence now lol .

I agree with @SurferJohn  

I don't know if you acquired these as projects or they are family pieces which would change my view otherwise. 

Cheers!

This is horrifying to read. The Montine could do with a clean, but the others all look age-appropriate. With respect, none of these are worth that much, but to destroy a watch that survived this long seems unfair.

I would say do whatever gives you the greatest enjoyment. They're your watches after all. If you do replace a case, though, be sure to be clear about that if you later decide to sell the watch.

To my eyes, at least based on the photos, all of those cases look fine. You can remove the movement and put the cases through an ultrasonic cleaner to freshen them up. 

I think a non-pristine case is actually a benefit of vintage. Having a case (or bracelet) that already has a few battle scars means that I don't obsess about it when I wear the watch. (Compare that to wearing a brand new watch, where every potential scratch or ding can induce a panic attack.)

I have replaced the case on one of my watches. The original plating had almost worn completely through; I don't have the expertise (or equipment) to replate it, and the watch wasn't worth the cost of paying a professional. I didn't get a new case, though, but rather found a broken version of the same watch on eBay.

They're your watches, do what you like.  That said, I'm in the "leave them alone" camp on this one.  A little touchup is all any of those really need.  And if you're looking to play around with watches, why not use something with less inherent character?  There are tons of parts for Seiko 5s out there, the possibilities are endless.  

All of the cases in your photos look good and unique, especially the Secunda with the striations. Most of these pieces look unique thanks to their cases while their dials are fairly standard.  My fear is that if you were to swap cases, the watches would lose much of their charming personality.

I would polish them up and keep them as is if they were mine. It's fairly easy to do too. Get some Turtle Wax Scratch and Renew, a microfiber cloth and a flat surface. Put the cloth on the surface folded in half. Put some of the Turtle Wax on the watch. Rub the watch in one area for a little bit then move it to a dry section and do the same. Polish the lens and all. You will be surprised about how many scratches that will come out. They come out nice. Keep repeating until you get the look you want. You will be surprised on how much the looks of the tired case will change. If you don't like them then change the case. Changing the case on a vintage watch can open up a can of worms that you may not want to deal with. Been there done that. LOL I just got this today. A polish and a strap change. I try to use used straps to keep with the look. I don't want an old looking watch with a sparkling new strap. Before and after. 

That Sekonda is amazing, needs a better bracelet or strap but other wise is great.

No Just light refer and crystals where appropriate but not full case swaps!

Beautiful, but subtle, transformation

Thank you everyone for your feedback. I’m going to leave them in vintage form and listen to all you Jedi watch people. 🙂👍😁