Feedline
I read articles like this, and I wonder just how long the antenna and coax has been up there.
This is a VHF system. I'll assume, based on when the low band radios around me were replaced with VHF, about 30 years. Has anyone swapped out the feedline since the first base install? If I took down that coax, would it snap like a twig? Is it so old that it leaks RF like a soaker hose? How much of the signal is actually getting out the antenna? Or into the reciever?
Same with the mobiles. Has the DPW been swapping out the same NMO mount and coax from old to new vehicle for the past 20 years. Does that coax got more bends and twist than a Tour 'de France bike route? Are the mechanics crimping PL-259's on with a pair of channel locks? (Don't laugh, seen it done).
There's probably nothing wrong with the handhelds that have such "terrible coverage". Let's face it, they either play or they don't. Same with the mobiles. There's a good chance the issue is just the base, or repeater site, needing a new antenna and feedline.