Stopping condensate pipe leak at junction Saunier Duval Semia Condens F30 E?

Believe pipe is leaking/dripping at very inaccessible junction. Appears to be a plastic screw thread which perhaps has a seal in. The apparatus directly above contains or is full of condensed liquid and has a tapered, very short,narrow opening at the top about the size of the end of a milk straw (Don't know what this is). Do you think the majority of the condensed liquid is still running away as my drip collector is not collecting much? Can I tighten the pipework? Cannot get my fingers to dripping area. Thanks