I brought a used Whirlpool Duet front loader and noticed that it's missing the detergent separator. The previous owner told me that I could only use powder detergent and now I realize why. Just wondering with this piece missing is it true or strongly suggested to only powder or can liquid still be used? I plan on switching to powder only but have some liquid still on hand that I would like to get rid of first but don't want to gum up the machine with liquid if the divider is a must have.

Here is the factory manual which will answer all of your questions: https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20L-78%20Duet%20Sport%20Washer%20Service%20Manual.pdf
That part should be easy to get cheap or, you should be able to bypass it even easier.

Thanks for the info it did help. I guess the separator holds the liquid detergent back instead of just going straight down the chute missing the opportunity for dilution. No dilution increases the possibility of gum. So I'll probably move forward with using powder until I can locate a "cheap" divider. Parts stores are selling them at a premium (~$27) so I will use powder while checking around for something more economical. Appreciate the response and manual.

Why not just dilute the liquid with a little water? That would be the cheapest way to solve the problem, unless you can cut out the plastic piece from a detergent jug. I saw what may have been that piece for $25.00 and thought that was way too expensive. If you can find someone with one then make a tracing and cut your own, or measure it from the machine, make a cardboard cutout, then make a plastic piece from the pattern. It couldn't be that hard to do.

Never thought about making a replacement. Just might give it try as you said should not be too hard. Also self diluting is a great workaround. Thanks for the suggestions.

Edit: I just searched for the complete dispenser and found several cheaper options and will solve this problem economically.