just buy a new magnet mount base.
they are 30 bucks give or take and it'll last you another 3 years.
Far easier and cleaner than trying to replace the coax etc.
The jacket on that cheap rg58 that comes with magnetic mounts is not UV 
resistant, it's not salt resistant or any of that stuff.  So, in a mobile 
environment where you get lots of both around, it'll break down after a 
while.
They're more or less disposable like allot of stuff these days.
Larsen magnet mount bases tend to have higher quality coax...I've got one 
that I've had for 13 years and the coax is still pretty decent on it...and 
it's been mobile for a good part of that time.
The only thing I've had to do to it in 13 years is open it up and cut the 
coax back a few inches at the feed point and resolder it...salt and water 
will find their way into the feed point no matter how well you seal it up.
This time I put some of that coax connecter sealer puddy stuff in there to 
help it last a while longer.
Anyway, when you run coax through doors and so on, it will eventually break 
down...it's a fact of life with a mobile installation like what you have.
Just replace the whole coax and mount assembly.  Bite the bullet and go on 
lol.
If you have to spend 30 bucks on your mobile antenna every 3 or 4 years, 
it's not that big a deal...10 bucks a year or less for maintinence isn't 
awful I say.

As for alternative mounting methods...you might be able to find something, 
but remember, a magnet mount in the center of the roof of the vehicle is 
going to be one of the best mobile antennas you can get.
other than a permanently mounted base where you drill a big hole lol. 
Anything other than the center of the roof type mount, either magnetic or 
drilled,  will yield lesser results in my experience.


73
Colin, V A6BKX