Timex T121 runs fast, about one minute per week. Why?

Lots of older watches needed to have the hands advanced 24 hours to advance the date one day. Fortunately most modern watches require the hands to be wound backwards to advance the date, often at the rate of a day per hour. A combination of the backward and forward winding of the hands made adjusting the day and date much simpler and quicker.

A few premium watches had a third position when pulling out the winder, a position dedicated to adjusting the day/date

to reset the date manually, pull the stem out to the second position to reset TIME; manually continue setting time until the date is on the correct day/date.
I had to do this to get back to the proper date when my timex was off by a week. Nothing else worked. 14 times around (twice per 24 hour day) and each time I passed "midnight" the date advanced.
blessings!

I had the same problem with the watch my wife bought me. On the mode make sure it doesn;t say T2 in the top right hand corner. if it does you are in the wrong mode. Hit the mode button until it shows the day of the week highlighted and a date and then go through the normal time set procedures. That worked for me.

go to the Timex web site "timex.com".

Scroll down to the bottom of the page and select "manuals/downloads."

Select "Product manuals downloads"

Enter you model number in the search box.

Choose your download from the list.

There is a solution, but you have to wait a bit. I'll contact Tissot tmrw and then will give you advise. It's 3.15 in the morning over here, so, need a little rest.

I don't know if I can help you out, but I can tell you that even a low quality Daytona, or Submariner copy can be adjusted. My 1992 Daytona copy is at about 10 sec a month fast. I read a **** load about the movement, and did the adjustment myself. Any watch shop that tunes watches can do it.

I don't know what year your Submariner is, but today Rolex is using a new main spring (it is now blue). I would think a replacement spring would be the most you might need, but a good tune-up should do the trick. If it is real, I would think about sending it to Rolex for cleaning and a tune-up ($$$).

if your caliber is automatic 7s26b something is wrong with the hair spring try a seiko service center anyway isnt something that you can fix by yourself!beware!far away from jewelers and local battery changers and other monkey magicians!automatic watch calibers are delicate and they ruine them!

There is nothing wrong with your watch. Probably it's the one measuring heart rate and pulse (heart beats per second).
Use your users manual to set the watch.
By the way: Timex is one of the worst watch producers.

It's not ok. Usual specs are +/- 1-2 secs a month, no more.
Try battery change first and if it doesn't help, go and see your nearest watcmaker to solve the problem.