I know the consensus is there is no screen in the hydraulic system of the L3130's or GL30's, but I've found a thread from 2007 on another tractor forum where it hints there may have been one.
I won't post the link here in the event it violates forum rules, but did send a private message to the OP with the link.
The link has a picture of the screen and a listing from the parts manual depicting it.
I haven't researched this further, but planed on looking for it on my L3130 the next time it's due for a fluid change.
I'll be happy to forward the link via private message or you can google L3130 screen Aug 12 2007 and it will be one of the first hits.