Advice needed re: two rads not working

[smudger]

I was recently asked to remove 3 old cast rads so the walls behind could be vandexed. The plasterer bent 2 of the pipes to get the skirting off (thanks). I replaced and reconnected the rads replacing damaged pipework. After fitting one lockshield had a small leak (not drip but wet to touch). but rads were working. I disconnected from rad and used some jointing compound and ok. But now that rad and one other side of wall not working. Pipe going into 1st rad is warm (before trv), rad cold, pipe after lockshield cold, both pipes and rad other side of wall cold. From what I can see, these two rads look like a single pipe system, but other rads working. System is pretty old and has never been flushed so I'm inclined to think that one of valves is blocked. What do you guys suggest should be my next step. Its my mates mum so cost is an issue as pensioner without much cash.

 

[mountainman]

Disconnect each rad valve in turn and open into a bucket, that will clear many blockages.

 

[Blake]

sounds like an air lock unless you used half a tub of compound on the valves

 

[SilentMike]

Take the head of the trv and and try and free up the pin.if it is a one pipe system then it sounds like that's where the heat is stopping.either that or hes dropped crap down the pipe too
plasterers aye!

 

[smudger]

Lol Blake, no just a smidge. Good advise folks, I'll start with silent's advise as easiest and work my way up to mountains (mainly as the rads weigh a ton!).
If you had been doing this would you guys have installed new valves?