Mk 40 speedmaster.. crown really stiff.

Dug · Feb 4, 2026

My MK 40 runs really well, about +4s a day, except that if I have it off the wrist for more than eight hours it can occasionally run out of reserve. Giving it a few turns in the morning sorts this but winding is very, very stiff. Anyway, cutting to the chase, to fork out for a full service or not? I'm guessing that, if it's just the stem seal, a cheaper service just to sort the seal would not be viable?
Grateful for any advice, thx

YY77 · Feb 4, 2026

I'm pretty sure you need a full service, when was the last time it was serviced?

Dug · Feb 4, 2026

YY77
I'm pretty sure you need a full service, when was the last time it was serviced?

Bought three years ago, but unsure of when last serviced. I know accuracy is not necessarily a testament to condition, but the winding apart it is all good, sets and resets as it should. Reluctant to get a winder, as I've always thought that it should not be necessary?

YY77 · Feb 4, 2026

Dug
Bought three years ago, but unsure of when last serviced. I know accuracy is not necessarily a testament to condition, but the winding apart it is all good, sets and resets as it should. Reluctant to get a winder, as I've always thought that it should not be necessary?

Your main problem is that after wearing the watch the mainspring hasn't been "charged" so service is surely needed.

noless · Feb 4, 2026

if you are lucky its just the gasket and crown tube that needs lubricating, but given the vintage of the watch and the unknown service history I would not be surprised if its the post of the reduction wheel in the automatic works, this not having enough lubrication/dried up lubrication results in a very heavy winding feel when hand winding and is reasonably common in 7750 based movements.

Most watchmakers should have no trouble servicing this particular movement, so you should be able to find someone who can do it for you without breaking the bank.

bsowers34 · Feb 4, 2026

My serviced last year 3523.80 will run out of reserve if I forget to turn the winder on for a couple days. And the crown is very stiff to turn. So you probably don't have a problem. The full service from Omega was about 900 in 2023.

Dug · Feb 4, 2026

noless
if you are lucky its just the gasket and crown tube that needs lubricating, but given the vintage of the watch and the unknown service history I would not be surprised if its the post of the reduction wheel in the automatic works, this not having enough lubrication/dried up lubrication results in a very heavy winding feel when hand winding and is reasonably common in 7750 based movements.

Most watchmakers should have no trouble servicing this particular movement, so you should be able to find someone who can do it for you without breaking the bank.

Thanks....that's really helpful. My favourite watch, so thinking it'll be a 'forever' keeper.

dsio · Feb 4, 2026

It’s a 7751 based movement so I’d get it serviced by a good independent with a parts account and save some money, 8 hours is way too short so it’s probably time

Dug · Feb 4, 2026

dsio
It’s a 7751 based movement so I’d get it serviced by a good independent with a parts account and save some money, 8 hours is way too short so it’s probably time

Thanks, I'll need to see if I can find a UK-based independent. I did quite a lot of research on winders before posting on here, but as with most things a range of opinions. Were I to have a full service, should I be able to leave off the wrist for 8 hours without a winder? I'm active most of the day.

noless · Feb 4, 2026

Dug
Thanks, I'll need to see if I can find a UK-based independent. I did quite a lot of research on winders before posting on here, but as with most things a range of opinions. Were I to have a full service, should I be able to leave off the wrist for 8 hours with a winder? I'm active most of the day.

definitely, it should be just about able to make 2 days from full wind (usually see 48 hours listed as the power reserve) and a days wearing under normal circumstances should get it pretty close to fully wound depending on how you move anyway.

I somehow missed the 8 hours bit the first time, I am extremely suspicious of the reduction wheel post oiling.

one more test though, with the watch horizontal if you hand wind it can you feel the rotor spinning? you should be able to feel it even though theres no see through case back here

Dug · Feb 5, 2026

noless
definitely, it should be just about able to make 2 days from full wind (usually see 48 hours listed as the power reserve) and a days wearing under normal circumstances should get it pretty close to fully wound depending on how you move anyway.

I somehow missed the 8 hours bit the first time, I am extremely suspicious of the reduction wheel post oiling.

one more test though, with the watch horizontal if you hand wind it can you feel the rotor spinning? you should be able to feel it even though theres no see through case back here

It is so stiff to wind that it is impossible to feel any feedack through the crown. Think it'll be a hunt for independent UK watchmakers, which do appear to be a rarity, and a full service.

bsowers34 · Feb 5, 2026

Dug
It is so stiff to wind that it is impossible to feel any feedack through the crown. Think it'll be a hunt for independent UK watchmakers, which do appear to be a rarity, and a full service.

As I said, mine is VERY hard to turn, and it has been fully serviced quite recently. Omega service is worth it IMO, it comes back looking brand new. And any repairs are included, plus warranty for 2 years.