Help with my leisure cookmaster 101 mk 2 (cm101nr)?

My kids spilt a load of dried cat biscuits all over the top of the cooker when the lid was up. Now when we use the grill or the oven on that side all we can smell is burning biscuits ?? It would appear that some of the biscuits have fallen down the vent grid thing at the back of the cooker. When i removed the panels off the back of the cooker i found that i still did not have access to thes vent areas ?? Does anyone have any ideas hwo i might be able to get access to the vent area in order to clean them out ??