RolandP
Thanks very much for pointing me in the right direction Roland. If anyone else has the same question, here is the luggage info from Matterhorn Gotthards web page:
Lockers
At the stations in Zermatt, Täsch, Fiesch and Andermatt you will find left-luggage lockers in different sizes. Prices vary between CHF 5.00 and 13.00 depending on the size.
Baggage that cannot be stored in the lockers can be deposited in the baggage hall in Zermatt and Andermatt during opening hours for a fee.