@slimwen , It may be time to give your printer a good cleaning especially the pick up/feed rollers. Use the links below for more troubleshooting and cleaning of the rollers, last link is to the printers manual. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
http://support.brother.com/g/b/faqend.aspx?c=us_ot&lang=en&prod=mfc240c_all&ftype3=1970&faqid=faq00000569_005
http://support.brother.com/g/b/faqend.aspx?c=us_ot&lang=en&prod=mfc240c_all&ftype3=1969&faqid=faq00000495_027
https://www.manualslib.com/manual/218949/Brother-Mfc-240c.html?page=107