Cracked Glass on Built in Hob. Tenant or Landlord’s Responsibility?

One tenant has reported her built in hob has a crack running the length of it and will need replacing.
The landlord is straight on to me, asking who is liable as it wasn’t cracked when the tenant moved in 4 years ago. Normally, as it’s a built in appliance, the landlord would be responsible but I’m not sure on this one, it could be accidental damage by the tenant.

View Related Handbook Page

Tenant Obligations

Through the tenancy agreement (or occupation contract), landlords may impose reasonable obligations on the tenant that affect their behaviour (including anti-social behaviour) and visitors.

Repairs, Maintenance and Fitness for Habitation

In addition to any repair responsibilities explicitly set out in the agreement, common law and statute will imply terms to the agreement