I replaced a Miyota 8215 movement...here's what happened

Before I talk about the process of replacing the movement, here's a quick background as to what led to this.

I was gifted a Rotary automatic watch by my wife, and I absolutely love it. I think it's a beautiful watch, it feels very well built, and ofcourse it's mechanical. Unfortuantly, it was dropped and the shock led to the movement inside being damaged. I could have had it repaired but it would have been silly (it would cost well over £300). For a basic Miyota movement, I couldn't justify the price.

So instead I decided to fix it myself. I had no tools so needed to buy those, along with a new movement. The original movement is the Miyota 8215, which is now discontinued. It has been replaced by the Miyota 8315 (it's got some nice upgrades like an increased power reserve and hacking). I bought a set of screwdrivers, hand removal tool, hand placement tool, dial protector, rodico, and some tweesers. These are the essentials (as well as a caseback removal tool, which I already had). These cost around £50 in total from Cousins UK (5* from my experience). Alongside these I bought the movement (also from Cousins UK), which cost around £55.

Now comes the hard part. First I took the movement out of the case by removing the screwed on caseback and taking out the crown (quite easy to do).

Next I used a dial protector, and using the hand removal tool took the hands off the watch. First mistake was not taking a picture prior to removing the hands, because there was a small piece which flew off when I did this and I have no idea how it’s supposed to go on. In the end, I left it off and everything seems to work. I’ve kept it safe incase I need it later.

Next, I had to take the dial off the movement, which I was able to do fairly easily by loosening the two screws for the dial feet. This allowed me to separate the movement from the dial.

Now it was time to put the dial on the new movement. Unfortunately, I also had to transfer the dial screws from the broken movement to the new one. This was really tricky, as the screws are absolutely tiny (holding them with tweezers and trying to insert them into the hole is almost impossible). This took me a good 15 minutes to do, and lots of mishaps like dropping them on the floor (crawling around with a flash trying to find them). I ended up using the Rodico to hold the dial in place, then hold the screw with tweezers in one hand and the screwdriver in the other. This was I could hold the screw in place and turn it at the same time. Finally, once they were in, I aligned the dial to the movement and tightened the screws.

The penultimate step was to place the hands. Remember that piece which flung off earlier when I took the hands off? I tried to initially place it below the hour hand, but it never looked right, so I decided to just leave it off. The hour hand went on fairly easily, but the minute hand took a few tries. I think it was at this point that I unknowingly broke the stem for the second’s hand. The thing is, I don’t have a loupe (another mistake), so I couldn’t even see the stem to begin with. I only realised it was broken after trying and failing countless times to get the seconds hand back on. In the end I watched a video on youtube where they show the stem with a macro lens. I looked for it on my movement and couldn’t spot it, so I definitely broke it at some point. I’ve had to leave the second hand off.

With the hour and minute hand on, I put the crown back in to check it everything works fine (it does), took the crown back out, put the dial+movement back in the case, put the crown in, and put the caseback back on. Job done.

But I found 1 last issue. Setting the date is very hard. Pulling the crown out goes straight to time setting, pushing it in goes back to the winding position. It’s very hard to set it to the date setting position, and I don’t know why. This was not the case when the movement was outside. It could be that the original crown stem is the wrong length? I’m not sure, but I have no intention of fixing it anytime soon.

Lessons learnt:

• Always use a loupe

• Take pictures at every stage of disassembly so you can reference them when re-assembling

• Do this somewhere that won’t be touched or disturbed by others

• Leave yourself plenty of time as it’s a very tedious job (took me over 3 hours or so)

• Be very gentle with setting the hands

• Watch plenty of youtube videos before even starting so you know what to expect

• Everything is tiny, it looks wayyy bigger when you watch youtube videos

• It’s quite fun and frustrating at the same time

• You will probably break something if you’re new to it like me, so do it on a cheap watch (or one that’s broken anyway)

I know it’s a long read but I hope it can help others if they’re attempting something similar.

Thanks for reading. Let me know your thoughts.