Oil pump leak

I am not clear on what happened. Did the O-rings get replaced at a 200 hour service and then the leak started or did the leak start after the 200 hour service and then the O-rings were replaced?

If it is the latter, then what was done at the 200 hour service that could have resulted in the leak starting or was it just coincidence?

This is the first time I see this engine.  I spoke with the owner who bought the o-rings from a local repair station. He belives they were original parts but he is not 100% sure.  He did the o-rings replacement 200 hr ago.   

I've ordered a genuine Rotax parts and I'm waiting the delivery.  Lets see if the new genuine parts fix the leak. I will not use the Loctite.

I'll take pictures during removal process and I'll post here to share wih you.

Thank you for your advise.

On the face of the oil pump surface there is a small hairline split where the two halves of the crankcase come together. The Heavy MM tells you to put a thin dab of the same sealant used on the gearbox flanges on this split line to prevent leaks.

I forgot to close this topic. I fixed the problem replacing all the o-rings and adding some Loctite in betwen the crancase junction

Thank you to all you guys for your help