Since you already know how to translate imperfect active indicative verbs, all you have to do now when you encounter an imperfect middle or passive indicative verb is render it into the middle or passive voice.

The imperfect middle indicative evluo,mhn may be translated:

(1) "I was loosing myself" (reflexive middle);
(2) "I was loosing for myself" (intensive middle);
(3) "I myself was loosing" (intensive middle).

Since the imperfect middle/passive indicative suffixes can indicate middle or passive verbs, the same verb evluo,mhn may be passive, in which case it would be translated:

"I was being loosed" (passive voice).

Remember that the imperfect tense often indicates ongoing action in the past. This is why we translate "I was being loosed," "I was loosing myself," etc.

The imperfect middle/passive indicative is made up of at least four morph slots: (1) the past morph, in this instance the epsilon augment; (2) the lexal morph, which in the imperfect will be identical to the present tense stem;  (3) the neutral morph, or connecting vowel; and (4) the suffix, which is derived the secondary middle suffixes. (see Black, Learn §94).

Observe the morph slots that constitute the following imperfect middle/passive indicative forms of  lu,w:

Observe how in the 2 sg we have the same situation that we have observed in the the pres mid/pass 2 sg, where an intervocalic sigma is elided. The connecting vowel e is linked to the secondary middle suffix -so, but the sigma is rejected, and the e and remaining o contract to become ou.

The imperfect middle/passive indicative endings:

You will notice that these are derived from the secondary middle suffixes. These will also be the same endings used for the second aorist middle indicative, but the second aorist will be formed from its own unique stem, and not the present tense stem (as it is in the imperfect).