Picked up a challenger VI last night from a local bar owner. Planning on reconditioning all o-rings but I noticed that the o-rings on the dip tubes do not look like the standard doughnut shaped ones that come in replacement packs. The o-rings on my dip tubes (will post pics tomorrow) are flat on the sides and have a cupped underside that fits perfectly on top of and over the bare post. Has anyone seen this before? I can't find any replacements online that look like this. Thanks in advance for any help.