After a series of flats 2 years ago I slimed my tubes, no flats since. However, the valve has gotten clogged and tire pressure has dropped. I ordered a core removal tool from Amazon, be here today. My question - am I going to get Slime everywhere when I remove the core to clean? Is there a position to put valve (Schrader valve, tire still on bike) in to minimize ? Anyone have any tricks or am I just inventing problems?