Ben Mattlin is author of the memoir "Miracle Boy Grows Up."

Its upholstery is cracking. Its motors are gunked up with mud, cat fur and other detritus. But deep down I really don't want to replace my 14-year-old wheelchair.

Not that it's a better ride than its many predecessors. I'm a lifelong chair user who has acquired a new chariot every seven years or so, till this time. The process always feels monumental, but now that I'm 54, it's nothing short of dispiriting.

Purchasing a wheelchair is not like buying a car or bicycle. Any wheelchair rider will tell you: Rarely do you get to see the chair beforehand, let alone take it for a test drive. You may get a demonstration, but chances are the demo wheelchair won't be the right size or meet your other particular requirements. Most wheelchairs, at least ones for people such as me, are custom-built.

In fact, you don't really choose your wheelchair so much as have it chosen for you — by physical therapists and sales reps. You can express preferences, of course, or refuse to follow their expert advice. But you'd better have a good reason, and play by the rules, if you want insurance to foot the bill — $15,000 is a steal for high-tech electric-powered models such as mine. After all, what do you know? You're just the patient.

My first wheelchair was a traditional, manually pushed one, and it was a thrill. I was 3, and due to a genetic neuromuscular weakness called spinal muscular atrophy, had never walked or stood. My wheelchair was a definite step up from the baby stroller I'd been cruising around in. I got to pick the upholstery color (green) and named it Wheelie Bird.

I was 10 before I was allowed a motorized Wheelie Bird. By "allowed," I mean that my neurologist determined that I wasn't actually getting any exercise from the manual conveyance, since I lacked sufficient muscles to propel it. A power chair, he reasoned, would give me greater autonomy and self-confidence. And indeed, it did. It also gave me a way to chase my older, able-bodied brother around our apartment, at least until he learned to shut it off.

But that first power chair was too ungainly to take outside. A manual job remained my primary means of transport. Wheelchairs have come a long way since then. The manual models are lighter and more aerodynamic; the power chairs faster, quieter and tougher, and they can be programmed for different environments and purposes. You might load one "driving profile" for indoors and another, zippier one for outdoor terrain. There are add-ons for tilting, reclining, elevating all or individual body parts, even standing.

But innovation certainly hasn't led to shopping ease. Before selecting my current chair, I did everything the right way. Instead of going to a wheelchair store, as I had previously — where, in memory, a fast-talking, brochure-brandishing salesman took one look at my insurance and decided I needed "the Cadillac of power chairs" — I approached a specialized wheelchair clinic at an in-hospital rehabilitation facility.

In weekly visits over six months, I was measured and evaluated by a horde of physical and occupational therapists who showed me various options, brands and accessories to accommodate my slackening muscles. My disability had progressed, as it's wont to do, to a point where a standard joystick control was no longer an option.

Just about everything else, however, felt like a fight.

"You need a different type of headrest," I was told.

"But I like the kind I have."

"No. It hurts you."

It didn't. But I followed most of their recommendations, and when the new chair arrived, almost everything had to be changed. Seat cushion, armrest and, yes, the headrest. The monster chair didn't fit in my apartment elevator, so the footrests had to be modified. The driving harness had to be propped up with dense foam or I couldn't reach it. On my first drive, I crashed in my living room. Then the powerful chair tipped over backward at the first incline, so the center of gravity had to be shifted forward.

In short, until myriad alterations were made, my brand-new, state-of-the-art machine had effectively immobilized — dare I say "crippled"? — me. It took another year of tinkering to get it right.

Is it any wonder I'm averse to rebooting this grueling procedure? I acknowledge that age has made me impatient. And perhaps I'm uncommonly complicated and picky. But a quick online survey of wheelchair-using pals suggests I'm far from alone. "My two-and-a-half-year-old 'new' wheelchair is still unusable, other than being a coat rack," one friend said.

But it's a losing battle. Sooner or later, this chair will give out. If by then I still haven't mustered the energy, patience and courage to replace it, well, I suppose I can always use the backup Wheelie Bird I keep in a closet for emergencies. It's only 37 years old.