Dad passed away - questions about his 1981 GMT Master

[Hurricane]

My father recently passed away and now I have his GMT Master that he bought while he was stationed in Germany in September 1981. The original price he paid was $650 in 1981.

The crystal is pretty scratched up and has a chip - he wore it every day. I believe he only had it serviced once, around 1998. I’d like to take it and get it serviced and cleaned up/polished but am wondering what I need to do to keep its value (and not hurt its value). It still runs. Any advice on what service I should have done (and not done) and where I should take it? (I am in the Northern Virginia/DC area).

I don’t have any plans to sell it but rather possibly wear it on occasion and pass it on to one of my sons. I’m a big fan of the watch and bought my own TT GMT Master II in 2012 that I wear daily to remind me of him. Now I would like to wear his watch in his memory, too.

Thank you for any comments.