I measure the old Seiko 6138 mainspring, to my positive surprise it’s very close to a ETA 2892-2 mainspring. 105X.115X420mm so I will order mainspring no: GR25341X
The movement is cleaned and ready to be put back together. I put the shock protection jewels back in place and see that the balance moves freely. The new mainspring goes into the barrel.
I put the rest of the watch back together and it looks and works great!:)