Star adventurer slipping/balance question

[VS6000]

Hey guys, been using the star adventurer a few times with a d810/70-200mm 2.8 lens and a few times in certain positions the big drive wheel on the front appears to not hold the load and roll around, thus losing the spot I had aimed at... being a rank amateur at this, is that the mount not holding the weight or does it simply need to be counterbalanced somehow?
Any help appreciated!

[astronobob]

There is a counter balance piece of kit available, may need to be used with the heavy'ish lens your using !!

https://www.youtube.com/watch?v=MprJ38JyUs0

http://ca.skywatcher.com/_english/02_mounts/02_detail.php?sid=68#

[VS6000]

Thanks mate! Figured that out, have also since got a 300 f/4 which is heaps lighter than the 70-200 which helps a lot!

[AstroJunk]

Interesting problem Tim. Mine grabs pretty solid.

I have used my canon + 100-400 zoom mounted to the small vixen plate with no issues whatsoever. I do find it a little more convenient to use the bar with the counter balance simply because I can do a polar alignment using the polar scope with everything in place :)