An Estwing hammer for £1 is a fantastic bargain, but like you said those leather handled ones really were a let down when the plastic washers broke in the stacked leather handle. I bought one years ago as a spare with the same problem, I ground off the end plate restacked the leather washers and had the butt end plate welded back on. Worked fine except for an irritating ringing sound when I used it to hammer anything. Finally gave it to a mate over here who needed a hammer, he was over the moon about it too.
You might not believe this but the one I'm restoring is my first Estwing (20 ounce) and the main reason I'm repairing it is because that one
has the ringing, the one I bought to replace it when those crappy few placky washers died doesn't
sing when its used.
For some reason I like that "singing" noise. Plus I've had that hammer ages and I'd like to keep using my first one.
Then there's the old one with the different style of head and very curved claws I bought for four or so quid, that's got a rattly handle as well, again its the plastic washers that are gone and the leather washers are fine.
I also have a 24 ounce ripclawed 16" long framing hammer which I use for shuttering and timber framing.
Oh and as that went missing for a while (someone at work
borrowed it when they went to another site for a few weeks, not realising it was mine despite the fact my name is engraved into the shaft

) I got a 25 ounce framing hammer as well.
I seem to have a fair surplus of Estwings.
3 number 20 ounce curved class, leather washer type.
1 number 20 ounce old style with the different head and very curved claws leather washer type.
1 number 24 ounce ripclawed framing type.
1 number 25 ounce ripclawed framing type.
Not to mention the fact that I can't go into my local secondhand tools place without picking up a chisel for a quid.
I've got masses of them, registered mortice chisels, paring chisels, skew chisels, many long gone manufacturers names and logos on them and quite a few Robert Sorbys which are still made and command quite a price.
Not one single proper mortice chisel like that above though. And I have been looking.
Not fussed enough to bother with Ebay though.
Realistically I just think I have a problem.