Ultra Fit USB 3.0 128Gb - intermittent drops un transfert speed


My new Ultra Fit USB 3.0 128Gb has suddenly started to behave strangely. I use it to store music for the car. It worked fine for almost two months, but two days ago I started to notice intermittent drops in transfer speed. The copy/sync process starts okay, but after a short while the transfer speed drops from around 9-10 Mb (the computer I use has only USB 2.0) to under 1 Mb ( usually to around 600 kb). It stays like this for several seconds, sometimes up to 10 seconds, then it gets back to the normal speed of 9-10 Mb. The result is that now it takes 25 minutes to copy 6 Gb. It took 5 hours to copy 80 Gb. I checked the logs of the sync software and they show intermittent slowdowns for about 10 seconds, on average.

I also have an Ultra Fit USB 3.0 64Gb, which is slightly older, and that one doesn’t have this problem. It took it less than 8 minutes to copy 6 Gb, using exactly the same files.

I have reformatted the larger drive, but there has been no change. It’s formatted FAT32, because that’s what the system in my car needs.

Does this sound like a disk defect? Should I request a replacement?

Many thanks for any suggestions.