I previously answered this on another site but I left off one possibility which still might allow this shredder to be "fixed".
It's not possible to break open this shredder without doing irreparable damage to the plastic combs between the cutting wheels HOWEVER, if the shredder problem is that it only will operate in reverse but not forward this indicates that the problem is in the switch assembly . This switch assembly can be pryed out the top of the shredder and could be replaced providing that you can find a replacement part.
Other than that, getting access to anything within the shredder container box has purposely been made to be impossible.
r.hand
October 2023