Your caliber{mechanism}is the 7t62.seiko have spare calibers.if your watch is in good condition and hands an dial is ok isn to expensive to change the mechanism.i was paid for the same repair 2 years ago with a new crown all seals gaskets new and the battery 125 euros{greece}.

Nice day to you! your watch is need of general cleaning and recondition ,efter cleaned and condition the machin ! be sure that the case back gasket is good and apply a small amount of silicon greas to avoid water damage ! close it verry tight ! good luck !god bless !