sudo sgdisk --zap-all /dev/sdX
sudo wipefs -a /dev/sdX

As with dd be very careful with the device letter because those commands can nuke your system if you get it wrong.

I think there's still some problem with your memory stick.
Can't really say what but it may well bring you problems when you least expect/need one.
Murphy and all that.

Like I mentioned before, you may want to back up whatever files are in the stick and nuke it.

In my experience, the best way to do it is with the command line to clear it completely and then format it.

Do sudo dd if=/dev/zero of=/dev/sdx bs=4096 .
It takes a while depending of drive size, just wait for it till the printout shows up.

--> Make sure you do this with the proper drive letter <--
There's no turning back from dd. 

To check the drive letter you can use lsblk, dmesg, gparted or all three, just in case.
You don't want to nuke your laptop drive.

Once this is done and unless there's a hardware issue such as a fake USB drive, it should be clear of whatever is going on and you can use gparted or the command line to format it again.

I'd use FAT32 as there's no advantage in using FAT16 unless you have a use case which requires filling it with +50% very small files.

FAT32 is understood by practically every modern device using USB and there's no 8.3 filename restriction.
ie: kingstonusb.txt ends up being kingst~1.txt.

Best,

A.

That is interesting, GParted declares it to be FAT16, but fdisk says FAT32?

sudo fdisk /dev/sdc -l                                                                                                                              
[sudo] password for mike:                                                                                                                                           
Disk /dev/sdc: 497.75 MiB, 521928192 bytes, 1019391 sectors
Disk model: DT Elite HS 2.0 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0408df67

Device     Boot Start     End Sectors  Size Id Type
/dev/sdc1          63 1017855 1017793  497M  b W95 FAT32

This scenarion reminds me of some cheap memory sticks I bought online a while ago, One said it was 1Tb, but GParted could only find 8Mb!

You're welcome.

Hmm ...
Would you please run fdisk /dev/sdc -l (as root or sudo) and post the printout?

Best,

A.

I think it is an issue with this specific USB stick, not with your installation.
Maybe a geometry issue?
Invalid cluster numbers?

My on-board memory is a bit foggy ...  8^|

You may want to try running fsck.vfat -n /dev/sdc1 for a read-only check and post the result.
or
fsck.vfat -a /dev/sdc1 to check the file system and directly fix it.

Another possibility would be to just do a full reformat with gparted or disks to FAT16 or whatever you need.

Best,

A.

* Edit: Rolfie beat me to it and explained it much better than me.  8^D

Your stick has an issue with the entries in the partition table:
1.) sdc: detected capacity change from 0 to 521928192
2.) sdc: p1 size 1019340 extends beyond EOD, enabling native capacity
3.) sdc: p1 size 1019340 extends beyond EOD, truncated

Unmount and run a file system check on that device.

rolfie

There is a whole lot of info when I run sudo dmesg, but the tail end of it with the latest insertion of the disk gives this:

[26546.252910] usb 2-1: new high-speed USB device number 8 using xhci_hcd
[26546.407795] usb 2-1: New USB device found, idVendor=08ec, idProduct=0015, bcdDevice= 2.00
[26546.407806] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[26546.407811] usb 2-1: Product: DT Elite HS 2.0
[26546.407814] usb 2-1: Manufacturer: Kingston
[26546.407817] usb 2-1: SerialNumber: 06F0444082903C42
[26546.410090] usb-storage 2-1:1.0: USB Mass Storage device detected
[26546.410739] scsi host6: usb-storage 2-1:1.0
[26547.429869] scsi 6:0:0:0: Direct-Access     Kingston DT Elite HS 2.0  5.02 PQ: 0 ANSI: 0 CCS
[26547.430424] sd 6:0:0:0: Attached scsi generic sg3 type 0
[26547.485593] sd 6:0:0:0: [sdc] Attached SCSI removable disk
[26548.712696] sd 6:0:0:0: [sdc] 1019391 512-byte logical blocks: (522 MB/498 MiB)
[26548.713155] sdc: detected capacity change from 0 to 521928192
[26548.714934]  sdc: sdc1
[26548.714961] sdc: p1 size 1019340 extends beyond EOD, enabling native capacity
[26548.716060]  sdc: sdc1
[26548.716101] sdc: p1 size 1019340 extends beyond EOD, truncated

But it is seen properly by other PC's, so what could be wrong? it is formatted as FAT 16 and seen as 512Mb by gparted.
Any ideas? Is it due to being FAT16?

Can you mount the stick manually:

sudo mount /dev/sdXY /mnt
ls /mnt
sudo umount /mnt # wait until this command returns the prompt before removing the stick

Replace X & Y with the drive letter and partition number for the USB stick (eg, /dev/sdb1). GParted should show this, I think. If not then check dmesg just after plugging the stick in.

That USB stick has FAT16 filesystem that I can see with GParted, and on other PC's in the house I can see it does have files on it.

How would I make it able to see FAT16 partitions?? its an old stick with not a lot of room so FAT16 is ample, would like to make the laptop more capable rather than reformatting. There may be others in the house with FAT16 on.