Messier M4 - NGC6121 - Globular Cluster in Scorpius - 15/05/2013 (Processed cropped stack)

I had been having guiding errors on several recent nights:
• 03/05/13 - 80mm APO f/6, 4X PowerMate with Orion ST80 and SSAG/QHY5 with SSAG ST4 cable(but no problems with 80mm APO f/6, Hutech FF with Orion ST80 and SSAG/QHY5 with ST4 cable)
• 04/05/13 - 200mm Bintel f/4 with MPCC with TS-OAG9 and SX Superstar with SX ST4 cable
• 11/05/13 - 200mm Bintel f/4 with 2X PowerMate with TS-OAG9 and SX Superstar with SX ST4 cable

I used M4 as a target with 6 guiding combinations to try to find the source of the problem:
• 6x 200mm Bintel f/4, MPCC with Orion ST80 and SSAG/QHY5 with SSAG ST4 cable
• 6x 200mm Bintel f/4, MPCC with Orion ST80 and SSAG/QHY5 with ASCOM/EQMOD
• 6x 200mm Bintel f/4, MPCC with Orion ST80 and SX Superstar with SX ST4 cable
• 6x 200mm Bintel f/4, MPCC with Orion ST80 and SX Superstar with ASCOM/EQMOD
• 6x 200mm Bintel f/4, MPCC with TS-OAG9 and SX Superstar with SX ST4 cable
• 1x 200mm Bintel f/4, MPCC with TS-OAG9 and SX Superstar with ASCOM/EQMOD

All performed faultlessly, so I am no closer to solving the problem :(
But, I did now have 31x M4 images, so I have stacked the best and have this image to show for the night :)

DeepSkyStacker 3.3.2 Stacked 85% (26) of 31 Images ISO 800 90 Sec, 39 DARK @ 120 Sec, 75 BIAS, 0 FLATS

Telescope - Bintel BT200 f/4.0 Newtonian (borrowed from Stephen Boyd) with Baader MPCC Coma Corrector, Hutech LPS-P2 filter, Canon 40D DSLR field 64' x 95', Ambient 11-10C.
EQMOD EQASCOM with Ascom 6 for mount countrol. Backyard EOS 2.09 for Image acquisition. Mount - Skywatcher NEQ6 Pro. Guidescope - Orion ShortTube 80 or TS-OAG9 with Orion SSAG flashed as QHY5 and Starlight Xpress Superstar as Guide camera and Stark Labs PHD auto guiding software using ST4 and ASCOM/EQMOD.

messierm4 globular clusterngcngc6121 m4 globular cluster

From 2013 Where to next?