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
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