The OEM temperature gauge on my '79 Invader 440 no longer works. I was recommended a Sunpro as a replacement but I'm told the model that fits are no longer made, so I bought a Bosch 8217. The gauge fits the dash but when the retaining nut is secure in the block, there is play in the probe tube so there is no seal. Shouldn't it fit tight? The metric adaptors don't fit. So, I'm wondering if anyone has some suggestions on how to get this to seal. Thanx in advance.