Yes, you can do this if you have a VCR that has a channel on the VHS
part of the unit that shows your DVD screen (see instruction manual for
better explanation). The Sharp unit that you have might have this
feature, if not then look at your instruction manual for how to hook up
the VCR part of your unit to an external DVD player. Good luck to you!
The DVD laser unit is probably faulty. It is probably not replaceable.