Replacing the Cog on a Jobo Expert Drum

[Paul_Wainwright]

I dropped the top to my 3006 Expert drum and managed to break off several teeth of the cog. In searching around my bag of spare Jobo stuff I came up with 2 cog assemblies that probably came with smaller drums that I own which have the option of using either a cog or magnet couplings. They look identical to the cog assembly on the lid of the 3006. In searching the LF forum site I've seen several old threads about repairing Expert drums, including one that alludes to actually removing the plastic cog assembly from an Expert lid, but it was an old post (2001), and I want a little reassurance before I apply force to try and pull off the cog assembly from the lid. Anyone else out there have any success with this?

[Gary Beasley]

Coigs are hard to remove without damage to the cog or the lid. However if you can break the old cog off the lid you can replace it with a new one apparently still available. I've found parts at Adorama and I think there is another supplier who carries parts.

[IanMazursky]

Omega Satter has a full catalog of Jobo parts on the site (http://www.omegasatter.com/Product_Listing.php?cid=3&bid=35&limit=150).
I think they might also be supporting Jobo products.
If you click on the Cog product they state:
The Cog Gears snap into the mouth of the tank lids and become a permanent part of the lid.
Note: they may seem like they could be removed because they use a compression o-ring system -- but they are not removable).

[Keith Pitman]

Rather than trying to force the cog assembly out, I would try cutting it into two or three sections. That should make it easier to remove. You'll have to be careful to avoid damaging the light block on the inside of the Expert drum. Also, don't cut all the way to the edge or you could damage the top of the drum. Just pretend you are doing brain surgery!

[dsphotog]

AFAIK the cog is molded into the expert lids.....
But if yours is too badly damaged to work anyway, go ahead & try to remove the cog.
Worst case you replace the lid.
This stuation brings to mind a version of Murphy's Law......If it jams, force it.....If it breaks, it needed to be replaced anyway.

[Paul_Wainwright]

Well, I finally got up the courage to try and remove the broken cog from the top to my 3006 Expert drum. It was messy but true -- the cog is removable after essentially destroying it. The cog is held in place by the tightest O-ring arrangement I've ever seen.

Here are some photos that may inspire others with the same problem.

First, here's the situation: I dropped my 3006 top and broke off some of the teeth of the cog:
http://www.paulwainwrightphotography.com/img/dsc_28.jpg

Using a pair of sturdy wire cutters, I removed as much of the remaining cog as possible (warning - wear eye protection!). Note: I saved the red O-ring in case I needed it as a replacement part in the future. Then I used a file to cut most of the way through the last bit of the cog (but I did not cut into the black O-ring, which I also saved):
http://www.paulwainwrightphotography.com/img/dsc_3135.jpg

A little persuasion with a pair of Vice-Grips popped what remained of the cog out from the top. The black O-ring is visible in this photo. Some firm hand pressure and the new cog snapped into place:
http://www.paulwainwrightphotography.com/img/dsc_3637.jpg

Here's what was left of the old cog, and what the replacement cog looks like:
http://www.paulwainwrightphotography.com/img/dsc_2739.jpg

Finally, I lubricated the red O-ring with some Jobo lubricant (part # 95465) on a Q-tip.

www.paulwainwrightphotography.com (http://www.paulwainwrightphotography.com/index.html)
www.colonialmeetinghouses.com (http://www.colonialmeetinghouses.com/index.html)