How to get Forerunner 305 data in Windows 10?

What happens when you click 'Add Device'? Nothing? Try reconnecting the 305 and cradle or use a different mini usb connector to a different port on your computer.

It waits (a long time) then there's an option of the different type of devices and I select Forerunner, then after some more waiting, I'm back at the beginning. I did try another port on my system; the device doesn't have a port, it only has 4 shallow pins at the bottom (that connect to the cradle).

Yes, I have a 305 and it connects fine to Garmin Express. You might also try cleaning the contact points on the back of the watch and the cradle using a pencil eraser. You can also swap on the mini USB connector that plugs into the side of the cradle, if you have another one.

I did so and although things have changed as the pitch of the device was higher (although that might have been because of the battery now partly charged). It still won't be detected by Garmin Express. At some point it was disconnecting and reconnecting from the USB port every few seconds, which I thought might have been from the software searching process, but I suspect it wasn't related to the software now.

Any idea what to do now?

Can you try plugging the Ant+ stick into a different USB port or even a different computer?

Agree with trying a different computer, but the F305 & 205 don't use the ANT+ stick. The only connector is the cradle with a mini USB port.

Is the Forerunner at least getting charged? When was the last time it worked? I tested with my own Forerunner 305 to make sure it's still working with the latest Garmin Express v7.8.1.0. I removed it and added it back without any issues.

If swapping ports, cradles, USB cable, and setting up Garmin Express on a different computer does not work, then consider a reset of the device. 

My Forerunner 110/205/210/305 is not charging or connecting to the computer | Forerunner® 305 | Garmin Support

Sometimes corrupt files on the device can impair the ablity to transmit data and a factory reset might be required (this will erase all user data)

1. Power the unit OFF.
2. Press the POWER and MODE buttons to the same time for 5 seconds
3. A pop-up box will appear saying “ARE YOU SURE YOU WANT TO ERASE ALL USER DATA?”
4. Select Yes
5. Put the unit outside with a clear view of the sky for a minimum of 20 minutes to get satellite data.
6. The unit is now reset.

Testing on a different port on my main computer was one of the 1st troubleshooting attempt I did. In my last post it was mentioned it was charging, although in parenthesis. I don't have access to another Garmin cradle, and possibly have a mini-to-standard USB cable but am not sure.

As I looked in the history a couple mins ago, it was fully charged; in it I can only see month & date, so no year. I'm almost certain it hasn't been used in 3 years, possibly 4, but it's very likely not more than 5. My other computer has GNU/Linux. I have irregular access to someone else's computer with Windows, but it might take a few days to test it there.

My F305 data was stored on an old computer of mine which I'm having trouble accessing its files, thus am not sure if what's on the device has been exported, thus would really prefer to keep the option of erasing the data as the very last troubleshooting step.

So I'll look for the cable and will try on the other Windows computer as soon as I can.

Your data is in the cloud so it doesn't really matter which computer you use. However, you need to be sure to log into the right account.

One thing to try is to take the 305 outside and get a GPS fix. That will sync the proper time/date and might align the stars for it to work.

My F305 data was only taken by the old software, see my 2nd paragraph why.