This is what your Float Needle Valve/s and seat assembly look like,
They come is a service kit like this,
https://www.ebay.co.uk/itm/403521485...IAAOSwR5diJLnL
The FNV sits in the middle of the floats attached by a small spring and metal pin.
You should still address the leaking Petcock though as it's not good to let it leak as it is. Where is it exactly leaking from ?
Also check the engine oil for fuel contamination.