I have stressed out.
I have a Clarke 205turbo (i think it is) which i got second hand.
i havent used it much BUT every time i do it gets clogged up where the feeder is.
I can only weld about 10cm if i am lucky.
Most likely your torch liner needs replacing. As a short term measure you could try blowing it out with compressed air. Change the liner, tip and shroud and set your wire-feed tension up properly, this should help things.Also, like Rich says, any rust at all on the wire will give you feed problems, if it's rusty, strip off the layers until it's good. Weldequip sells all torch parts. PM him if you need any bits.
The tension on the rollers should be set so that they skid when the wire sticks. I found that very difficult on mine, the adjustment was very sensitive.
Forget compressed air - new torch liner will work wonders. Follow the wozzaah link and go for a steel one. Some instructions and troubleshooting (for a different welder) here