External WD 1 TB will not connect (mount) on a Mac

I have had this problem for a while where the external WD drive doesn't want to connect or be visible on the Mac. I thought it was the cable and fiddled about with that but no. Occasionally it would connect but it didn't follow a pattern, or didn't seem to. I am using the drive as a Time Machine backup.

I may not have fixed it entirely but I can now get it to mount and indeed it has mounted correctly ever since - a few times.

I went to the Disk Utility app and the 1 TB WD drive was being found. It was in the left-hand pane as  shown in the image below.

The below image shows the drive in its working state.
In it's error state it was displaying the text: disk1s3

I went to the Terminal and ran the command:

diskutil list

This provided me with the following:

John-Mac-mini:Volumes John$ diskutil list

/dev/disk0

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *500.1 GB   disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:                  Apple_HFS Macintosh HD            499.2 GB   disk0s2

   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

/dev/disk1

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     Apple_partition_scheme                        *1.0 TB     disk1

   1:        Apple_partition_map                         32.3 KB    disk1s1

   2:                  Apple_HFS                         1.0 TB     disk1s3

I then mounted the drive:

John$ diskutil mount disk1s3

I noticed immediately that the drive mounted on the desktop and in the DiskUtility app.

Note that the disk identifier may be different for your setup. If you are unsure, look at the disk Utility app where I have drawn the red rectangle.

As I say, I haven't fixed this because at the next power off it may refuse to connect again.

When running distil list again the drive partition is given a name ' My Book Time Machine' as expected. I am not sure if this name is only available after mounting, and therefore it is correctly blank before mounting, or whether that is a part of the problem.

/dev/disk1

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     Apple_partition_scheme                        *1.0 TB     disk1

   1:        Apple_partition_map                         32.3 KB    disk1s1

   2:                  Apple_HFS My Book Time Machine    1.0 TB     disk1s3

How to test memory in OSX

If your are experiencing an occasional random rebooting then maybe there is a memory gremlin.

 A pretty good old-school memory test can be done by downloading memtest and installing it, then starting your Mac in command line mode (single user mode), and then running memtest.

1. Download memtest
2. Install. It will be placed in /usr/bin/
3. Shut down the mac and restart keeping the cmd and s keys depressed. It will boot into single user mode.
4. Run memtest by typing, memtest all

Where to get memtest

It can be found in a few places and I have used it from here before, http://www.optilabs.eu/download/memtest_422.zip

Multiple tests?

memtest all n

:/ root# memtest all 5

(Running 5 times took over 5 hours)


Example Output

Memtest version 4.22 (64-bit)
Copyright (C) 2004 Charles Cazabon
Copyright (C) 204-2008 Tony Scaminaci (Macintosh port)
Licensed under the GNU General Public Licence version 2 only

Max OS X 10.8.2 (12C60) running in single user mode
Memory Page Size: 4096
System has 2 Intel core(s) with SSE
Requested memory: 3864MB (4052697088 bytes)
Available memory: 3864MB (4052697088 bytes)
NOTE: Memory request is too large, reducing to acceptable value...
Allocating memory: 3756MB (3939221568 bytes) at local address 0x0000000101000000
Attempting memory lock...locked successfully
Partitioning memory into 2 comparison buffers...
Buffer A: 1878MB (196910784 bytes) starts at local address 0x0000000101000000
Buffer B: 1878MB (196910784 bytes) starts at local address 0x000000017665e020

Running 5 test sequences... (CTRL-C to quit)

Test sequence 1 of 5:

Running tests on full 3756MB region...
 Stuck Address       : ok
 Linear PRN          : ok
Running comparison tests using 1878MB buffers...
 Random Value        : ok
 Compare XOR         : ok
 Compare SYB         : ok
 Compare MUL         : ok
 Compare DIV         : ok
 Compare OR          : ok
 Compare AND         : ok
 Sequential Increment: ok
 Solid bits          : ok
 Block Sequential    : ok
 Checkerboard        : ok
 Bit Spread          : ok
 Bit Flip            : ok
 Walking Ones        : ok
 Walking Zeroes      : ok

Cleaning the Mac Mighty Mouse

They do get clogged up. That's the only pain with them - they weren't designed to be cleaned and Apple didn't expected them to get clogged with gunk.
Years of scrolling down and not able to scroll up ensued.

How to Clean - attempt ONE.

1. turn the mouse upside down
2. Put the ball on a sheet of white paper and quickly move the mouse around for a minute or so making sure the ball is being exercised.

This sort of works sometimes. Though often just as a brief respite.

How to Clean - attempt TWO.
When it's all got too much and attempt one isn't enough then:

Tools needed are few, I used the screwdriver of a Swiss Army knife and a tiny phillips screw driver and glue to put it back together.

There are 4 tiny rollers in the ball device. When you take the device apart make a note of their orientation. You can review it in the video.

How to do it, see this helpful Video.