Error When Trying to Resize Samples Partition

That did the trick! Thanks so much. I could kick myself, I had seen the ntfsresize command when I was googling, but obviously hadn't tried it.

I did need to unmount the partition, run ntsfsresize, and then I rebooted. I've since uploaded some samples, and gotten them to run, so all is well! And my needs are pretty modest, so this old Pi may just manage! 

For reference, her is a cut/paste of how it went:

root@samplerbox:~# umount /dev/mmcblk0p3

root@samplerbox:~# ntfsresize /dev/mmcblk0p3
ntfsresize v2014.2.15AR.2 (libntfs-3g)
Failed to set locale, using default 'C'.
Device name        : /dev/mmcblk0p3
NTFS volume version: 3.1
Cluster size      : 4096 bytes
Current volume size: 134214144 bytes (135 MB)
Current device size: 6239027200 bytes (6240 MB)
New volume size    : 6239023616 bytes (6240 MB)
Checking filesystem consistency ...
100.00 percent completed
Accounting clusters ...
Space in use      : 111 MB (82.6%)
Collecting resizing constraints ...
WARNING: Every sanity check passed and only the dangerous operations left.
Make sure that important data has been backed up! Power outage or computer
crash may result major data loss!
Are you sure you want to proceed (y/[n])? y
Schedule chkdsk for NTFS consistency check at Windows boot time ...
Resetting $LogFile ... (this might take a while)
Updating $BadClust file ...
Updating $Bitmap file ...
Updating Boot record ...
Syncing device ...
Successfully resized NTFS on device '/dev/mmcblk0p3'.
root@samplerbox:~#

I then rebooted and all was as expected---the partition had been expanded. I probably could have just remounted... but a reboot is so quick that I tend to reboot, and remove one more opportunity for error.

Thanks so much for the help!

Chris