I assume the circumstances were that the Tenants claimed that he/she vacated because the lift was out-of-service.
That being the case, that Tenant would have been hard-pressed to convince a reasonable person (or even the N.S.W C.T.T.T.) that that was the only option; otherwise every resident above level 2 would have done likewise!
If you're the Landlord, you could have offered to reduce the rent during the 10 week period that you describe; not that you were compelled to, just as your Owners Corporation would not be compelled to compensate you in that or indeed any other similar circumstance, if that's what your seeking advice about.
Strictly speaking and in the circumstances that you describe, Tenants can voluntarily terminate Leases with 14 days (fixed term) and/or 21 days (periodic term) written notice. In the former case, and except in a few excepted circumstances of which a lift upgrade is not one, the vacating Tenant is required to keep paying rent until the Landlord finds a new Tenant or until the fixed term expires.
So in summary – the answer is that:
- In limited circumstances the Tenant is responsible, in which case an application for costs could be made to the CTTT or similar.
- The Landlord could make a Claim for lost rent on any Insurance held
- The O/C (of which the Landlord is a part) is not responsible