Hi. I have an Alko powerline ride on mower. Brigs & stratton engine. I was in the middle of cutting my lawn and after emptying the grass box I tried engaging the blades to start again but the engine started cutting out and back firing. Even if I let the clutch out fully it would start to die. Reading about this on sites like this I checked all the fuses and the safety switches on the Grass box - seat & break and they all seamed to have continuity. I rang an old guy near me that can fix anything and he told me it was the grass box safety switch. I told him I checked them and they seamed fine but he just said " they can be temperamental" Giving the fact he knows what he's talking about I changed it and it worked. So if you think the switches are ok, they might not be. My mower is working perfectly again. Replace safety switches first.