I had the same problem where the time knob broke. I filled in a claim form on the Oster Website and they answered within 3 days saying the timer knob was discontinued and no longer available. They proposed to replace the whole toaster-oven with another model 6073-33 which I received last week. I've to say that their customer service was amazing.

FIRST UNDERSTAND , there is nothing about this oven thats OSTER except the name oster subcontracts the work out to a china co that makes the oven and put there name on it out of the factory in china it costs $4.00 shipping to the USA $1.00 oster gets them and ships them to wallmart and bills wal mart 24.00 and you buy it and its 36.00 .... its still only a 5.00 oven to oster why would oster ever sell parts for a 5.00 unit ? you think 36.00 is a lot ? in my shop i have a proctor silex toaster made in 1972 that sold for 29.99 in 72. back then that was a lot of money ,if you needed parts you could get them ....... todays appliances cost nothing to make thats why you cant find anyone that sells parts for them , there are no parts books on this oven ,in this country . i think your stuck