Q: I really love my sofa and don’t want to get rid of it, but it has a very old, heavy and uncomfortable bed mechanism. I’ve slept on other sofa beds that were comfortable, but they were newer. Is it possible to change a sofa bed into a different type, or can a sofa bed be turned into just a sofa (without a bed in it)?

A: It is often possible to remove a bed mechanism and still have a sofa, provided you rig up a way to support the sofa seat. But first, you might want to see whether you can make the bed more comfortable.

The problem is often a sagging mattress support system, coupled with support bars that dig into sleepers’ backs or hips. To provide more uniform support, try slipping pieces of ⅜- or ½-inch-thick plywood under the mattress when the bed is pulled out. You don’t need one big piece, which would be difficult to maneuver and store. Pieces 16 inches wide would work, provided they are long enough to bridge the bed’s bars.

Connect them with hinges made of duct tape, so they stay aligned and fold up for storage. Or buy a ready-made solution. The Sleeper Helper ($119.99, sleeperhelper.com) has connected panels that fold out to be 48 by 48 inches, suitable for full- and queen-size sofa sleepers. Folded, the panels are ⅝ inches thick, so you can tuck the package into the mattress when you put away the bed. The Stratiform sofa bed bar cushion ($89, Amazon) is made of high-density foam about one inch thick. It’s 54 by 28 inches and fits between the bars on many sofa beds.

It’s also possible to replace the mattress on a sofa bed, which can make a huge difference. The website mattressinsider.com has an overview of options, with pros and cons, as well as measuring tips. Besides matching the width and length of your existing mattress, be sure to also note the depth.

Instead of measuring the thickness of your existing mattress, which might be less than when it was new, the website replacement-mattress.com recommends measuring between the top and bottom of the bed frame when it is pulled out but still folded. (The site has an illustration that shows the exact place to measure.) Both sites sell replacement mattresses, with prices varying depending on density and measurements.

If these solutions don’t work or you decide they are not worth trying, the simplest solution is to keep using your couch as-is. You don’t say why the weight is an issue, but if you want to make the couch easier to move, so you can clean underneath or rearrange furniture, get furniture sliders, which fit under the feet of the sofa and make it easier to push around. A four-pack of Magic Sliders that work on wood, ceramic tile or carpeting costs $19.39 at Home Depot.

If the weight is an issue because you are contemplating a move, removing the bed mechanism probably would reduce the cost, especially if stairs are involved. Matheus Cruz, who works for Two Men and a Truck (twomenandatruck.com), a ServiceMaster moving company with franchises in most states, said only about half of all sofa beds have mechanisms that are easily removable.

You’ll find a variety of how-to instructions online. Some suggest placing the sofa on an end or on its back, then removing the dust ruffle, so you can find the bolts that attach the bed frame to the sofa. Other sites say to extend the bed first. The variety makes it clear that not all sofa beds are constructed similarly, so do some sleuthing. You might also be able to hire a moving company to do the removal for you. Cruz suggested calling small, local companies, rather than a nationwide one like his, which has a minimum charge of $800 to $1,000 for three hours.

Beds often have a spring mechanism that engages when you fold up and push in the bed. If you are removing the mechanism in the folded position, tie it with rope first, so it doesn’t accidentally spring loose while you’re working on it. The seat cushions on a sofa bed typically rest on the bed mattress, so if you remove the bed, you will need to add support for the sofa seat. Maybe a clever handyperson service could help you with that.

Have a problem in your home? Send questions to localliving@washpost.com. Put “How To” in the subject line, tell us where you live and try to include a photo.