Leaking oil filter

Just to update on this...

changed the oil filter over and all seemed ok. A couple of days later there was a trickle of oil down the nose leg again. Oil was accumulating at the bottom of the filter and on the hex bolt beneath (under). 

Knowing it wasn’t the oil filter this time I investigated a little further and found that two of the bolts holding the gearbox together were loose. Tightened them up and the oil issue has gone! They were the bolt shown here (and the same on the opposite side), image not mine. The one circled in the image was the looser of the two. 

Explains why it was dripping onto the oil filter and lower hex plug/bolt.

did an engine run which had no leaks, so hopefully sorted it!

Although tightened, I was thinking of using a thread sealant to make it a little more secure. Is there one recommended (or is it recommended) for this part?