Jobo ATL-2 Rinse Problems

I've got a Jobo ATL-2, which is working flawlessly except for a small problem with rinsing:

It seems that my rinse water is not draining completely. It is draining most of the water, but some remains which accumulates with each addition. I have seen the problem both with a 1520 drum (to a lesser degree) and a 2850 drum. If I do a 15-minute final rinse for example, there will be 1-2 liters of water in a 2850 drum at the end of the process, after it has raised and lowered the drum for the final "drain".

It's not a critical problem right now, because the processes I run at the moment do not have rinses mid-process. I can just empty the excess water manually. However, I am worried that if I do something with a mid-process rinse, I could end up diluting chemicals, and then not be able to reclaim them. I've searched this forum and others, and haven't found anyone mention this same problem.

Any ideas?

This is a problem that Jobo dealt with a while back, when the first Auto lab machines came out.
The solution is quite simple - you need to drill a small hole at the bottom of the tank to allow more air exchange when the tank is draining and thus drain the tanks faster.
I you ever need to use the tank for inversion just plug the hole with some silicone.

Also adding the "vent tube" will help as well (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=271301659027&ssPageName=STRK:MESE:IT)

Thanks CatLABS!

Just a couple questions though:
1. Where is the vent tube installed? In the expert drum spout where there is currently the red plug?
2. Wouldn't drilling a hole in the bottom of the drum defeat the light-tight design of the drum?

EDIT:
Never mind #1, I see the picture showing the installed vent tube.

The drill method cant be utilized on Expert drums. In all other drums, the center core will prevent any light leaks and keep the tank light tight. If you are using print drums or expert drums, the vent tube should help, and you should use the smallest possible amount of liquid when running the print tanks, With expert tanks you just have to let the little red tube do its thing.