My Visconti Homo Sapiens Bronze Age oversized lava fountain pen has recently started to leak ink which gets on my fingers at the forward end of the section-- no burping just ink around the finger surface edge of the section. I've had this pen for over 2 years now and I like it very much since the EF nib is very good (fortunately!). Since I don't own the special Visconti tool to unscrew the nib-feed nit, I, now and then, use my fingers to unscrew the nib-feed housing unit doing this to use a blunt tipped syringe to squirt water into the ink reservoir in the barrel. I don't know if the nib-feed housing unit removals I've done have led to this recently started leaking. I think there's a tiny O-ring at the lower threaded barrel-end of the plastic nib-feed housing unit. Could that tiny O-ring be worn out? Could silicone grease solve this problem but if you say "Yes, use that grease", where on the plastic nib-feed housing unit would I smear some of it on?