Had a great result with my old (16 yrs to me) seiko diver 6306,7001 , six years ago it was dropped at customs, it sped up stupidly, two hours a day, no amount of regulating would sort that out, and it's been in a drawer since.
I recently found it and the average price is £120 for service. grrr!!
then decided to look for a movement, found the exact same movement in a very undesireable case........fully serviced, far cleaner than my one, no rusting/water damage or pitting, and delivered for £13 ALL IN!!! . ( it did take 3 weeks to get here)
been checking and regulating for 3 weeks, it is tickettyboo!!!
so spent some cash (£30) on a high dome sapphire with a blue AR crystal.
which looks better in daytime...