Thread:User talk:CodeCat/*klengan - to sound/reply

e becomes i when followed by a nasal and another consonant, so *kleng- is not a possible root syllable in Proto-Germanic, it would be *kling-.

I can't say much about the verb type. According to the Etymologisch Woordenboek van het Nederlands, this is in origin an onomatopoeic word, so it's not surprising that there are many kinds of derivation. What's more, the verb looks like it should be strong class 3, based purely on its shape/sound. So this could have actually caused it to become strong if it wasn't already. This means that the fact that many descendants are strong class 3 does not necessarily mean that the original verb was too.

There are also several verbs in your list which cannot be descendants of this. Those are the forms with -k- instead of -g-, which must come from a separate related verb with -k-. Furthermore, Old English clynnan, and probably also Old Frisian klinna (if it's the same verb) must derive from a different verb too, something like *klunjaną or *klunnijaną. Old Saxon klinke is not even a verb, as Old Saxon verbs always end in -an or -on.