I think you're a bit confused here .. take it step by step .
a) first of all the final verb phrase is
to shed light on, meaning
to throw light on. So
shed here is the infinitive or base form - which is by chance unchangeable in the past (2nd form) and past participle (3rd form) -
shed, shed, shed - similar to
put, put, put
b) then you have the verb
to help which can be followed by two constructions : 1) the infinitive with to :
It helps to shed light on ... or 2) the bare infinitive : it
helps shed light on ...
c) and then you have
may, which must be followed by the infinitive - in this case
help :
it may help ..
so : put it all together and you have ...
may + infinitive (ie help)
help + infinitive (ie shed)
may help shed
Compare it with other examples :
This helps to clarify the problem or
This helps clarify the problem becomes
This may help to clarify the problem or
This may help clarify the problem (I hope!)
The form
clarify has nothing to do with
may - it's dependent on
help - and certainly isn't a third form (ie past participle). It's the infinitive.
I hope that helps to shed light on the structure
