I use this gauge assembly when I want to shoot tethered to one of my tanks. Today I discovered the cap that keeps the oil inside had come off of both gauges and the oil was all over the regulator and a bunch of other stuff that I kept stored in the same drawer. Do you think any oil seeping into the regulator would affect it's performance? Are gauges typically filled with mineral oil, and all I need to do is fill them back up enough to cover the gauge needles?