BUT - in the Corruption section it says He suffers the effects of spell failure and corruption, so that could be taken to mean roll on both charts.
I'm thinking that spell failure just means the spell fails to go off... you wouldn't role on the spell fumble chart unless your corruption roll indicates you do.
Most spell failures also result in the loss of the spell. E.g. a results of 1-11 on "Animal Summoning" means the spell is gone, you can't cast it for the day without risking spellburn.
But also note:
A spell check result of a natural 1 is always a failure. A result of 1 also results in corruption or disapproval, as described below.
Failed spellburn: Any magic-user who rolls a natu- ral 1 on a spell check while using spellburn suffers the loss of ability points and the associated corrup- tion (see below), and also loses 1 point of ability score permanently.
Natural 1s are tremendously punishing for wizards and much less so for clerics.
Basically, ordinary D&D makes clerics into healers and wizards into fantasy-engineers who can remold the world.
DCC makes wizards into terminal cancer patients who work as maintenance men in Fukushima. They're *going* to get horrible deformities and die, probably sooner rather than later.
By contrast, clerics are relatively safe. They risk disapproval, which is much more forgiving than corruption.
So far, it looks like the only good reason to have a wizard around is to cast "Patron Bond" on characters who have a better chance of surviving to 10th level. Patron Bonds for non-wizard classes have some risks, but they're not guaranteed suicide pacts.
Playing a wizard in DCC basically appears to be "taking one for the team." He has to give the other player-characters permanent power-ups as soon as possible, because he will probably be dead before 2nd level.