Did you press and hold the reverse button? If you did, then some link between the button and the feed dog is damaged. That may need to be repaired by a professional. However, the parts may not be available for this machine. I have at least one source for a service manual for the 5018: https://www.sewingpartsonline.com/service-manual-janome-5018.aspx . This particular online store has some of the more common parts for the Janome 5018.
Janome has the manual for the 5018 Decor Excel on the retired machine support page: https://www.janome.com/support/retired-machine-manuals/ . This is in the right hand column under Other Machines. The current link to the manual is https://www.janome.com/siteassets/support/manuals/retired/other-models/inst-book-5018-ennose.pdf . The Reverse button is described on page 7 (page 18 of the PDF).
Answers & Comments
Did you press and hold the reverse button? If you did, then some link between the button and the feed dog is damaged. That may need to be repaired by a professional. However, the parts may not be available for this machine. I have at least one source for a service manual for the 5018: https://www.sewingpartsonline.com/service-manual-janome-5018.aspx . This particular online store has some of the more common parts for the Janome 5018.
Janome has the manual for the 5018 Decor Excel on the retired machine support page: https://www.janome.com/support/retired-machine-manuals/ . This is in the right hand column under Other Machines. The current link to the manual is https://www.janome.com/siteassets/support/manuals/retired/other-models/inst-book-5018-ennose.pdf . The Reverse button is described on page 7 (page 18 of the PDF).
I hope this helps.
Cindy Wells