Hub seals are quite reliable. Considering the number of miles I have put on both my coaches and how few I have replaced over 20 years is a testament to their reliability.

But I noticed on Jim's tag axle brake chamber signs that the tag axle seal leak is not recent. One of the inspections I think everyone should do is to look for indications of a leak. A drive axle hub seal leak is easiest to note from beneath the coach so every time the coach is lubed a close look at the inner wheel will be the easiest way to check that. Tag and steer axle leaks can be easily checked any time the tires have their air pressure checked. Stick your finger through a hole in the wheel and feel the wheel. If all you get is dry brake dust, no leak. If your finger has grease on it, the seal is leaking.

At that point checking the fluid level in the hubs becomes critical until the problem can be taken care of. A little oil in the hubs in a timely manner will save some serious repair money. Do not overfill the hubs, just insure the oil level is at the bottom of the viewing area, and make sure the pin hole in the cap is open so there is no pressure build up in the hub.

Never ever allow a hub seal replacement unless the technician (or you) pre-lubes the bearings, especially on the drive axle.