Mk2 heater doesnt blow as hard on hot as it used to

Well my heating was working fine since I replaced the valves (with 2nd hand ones) untill last night when I was driving in central London the bloody heating packed up!!
Was going to buy some new valves but they cost too much, so Im just going to bypass them.

 

Going to be binning mine tomorrow!


Only problem i have is that the windscreen vent on the drivers side (there are 4) is really weak, hardly anything blows out of it while the one next to it blows a gale!

Is that section individually sectioned off? or is it just one straight piece? as i have stuck coat hangers down there to see if there was a blockage but could not find anything, and yes i have blocked the others up and it's still the same!

Any ideas?

 

mines similar, but with a new matrix and bypassed valves the furnace coming from the middle vent is more than enough to clear the screen.

 

Hopefully with the pipes in it will not matter then! cheers!