Gas central heating radiator leak

[frankino]

Decided to save money by painting room myself instead of calling in decorators.
Drained radiator 1st time then refitted....horizontal fitting leaking : put thread tape on.....now got leak on vertical metal joint.
I think I'm in big trouble as this is not interchangeble(I read in an article).
Is there any sealant I can buy or am I stuck with draining system and having to renew pipework?
Thanks in advance

[htg engineer]

If all compression then it should be repairable, if it's been over-tightened you could try PTFE tape on the olive/ring.

htg