Seiko DX [6106-7619] that celebrated escape from Soviet regime

My grandpa (Ukrainian), born in the 1946 migrated to US with his family in the 80’s.

After landing his first job as construction worker to mark the new beginning to his life, he celebrated with this Seiko DX. If I’m not mistaken, it happens to be my dad’s birth watch as well - 1974.

It seems my grandpa liked that watch so much he didn’t take it off at all. All these years of wear are clearly visible on it.

I want to gift that watch to my father for his 52nd birthday next year. I definitely want to replace the crystal and the bracelet, I’m fairly sure I can polish the case myself, but don’t know where I can find the parts for such vintage watch (I live in Poland).

Anyone here happens to know a thing or two about these watches and parts for them?

Thanks in advance!