cazalea[Seiko Moderator]
20750
I can make one comment on "received a strong impact"
I have serviced a number of Rolexes, and once got a watch that had flown out of the owner's coat pocket onto the locker room floor, which shattered the crystal.
When we finished servicing the movement, we couldn't get the new round sapphire crystal into the slightly oval-shaped case.
We ended up chilling the glass in a freezer overnight while keeping the case warm.
We were able to just force the glass into the case but I certainly wouldn't recommend this or expect it to retain water resistance.
So beware of changing the glass if you don't want be told "you also need a new case".
I'd keep it as it is, or ask a local watchmaker to do a simple oiling and adjusting.
Cazalea