Error 50 afte paper jam
The following is an extract from the Brother Service Manual that covers your machine:
"Error Code 50 & 51:
The purge cam switch
does not come ON or OFF
even after the purge cam
has been driven by the
specified number of
The manual lists seven different causes, best case being the need to clean part of the mechanism, the worst case being replace the whole main electronics board !
Unless you have very good skills for dismantling such a complicated machine*, your choices are take it to a Brother Service agent who will probably charge you more than a new machine, or bin it - sorry !
* If you want to have a go at dismantling it, the service manual can be bought on eBay for about £5. If you don't want to spend that much, I can supply you a .PDF file copy for £1 - just post back here and I'll sort it out.