The option is found under "Missing mnemonic" and you have to select the "Electrum" type from the second drop  down on the right, then select the wallet type that Electrum was using from the drop down that appears after that. Make sure to enter the correct BIP32 path. Example 6 and 7 are Electrum mnemonics missing 1 and 2 words respectively.


A couple of points:
* Electrum mnemonics are 12 words by default
* You have to know the position of the missing word. But if it is only 1 word you can manually change the position from start to end and click Find 12 times, it should all take 12 seconds.
* You have to know a derived child from that wallet (it can be a child private key, public key or an address)
* Setting the path correctly is very important. When setting the wallet type (Electrum mnemonic type) FinderOuter automatically sets the correct path for that type but you have to enter the index of the child key you entered (eg. if you entered the 10th address you have to add 9 to the end of the path)