Ours work as The Clock Meister has suggested. I do know some will loose their charge over time. We had an 85 Olds that used them to open and hold up the trunk lid. I can't count the number of time I gave blood or got a knot on the top of my head before I finally replaced them.
Most sizes are available at auto parts stores and cost $13.00 - $26.00 depending on the size.
I want to thank everyone for their reply. My Sightseer was in for some major repairs and I explained the gas springs did not hold up the bed. Listed under correction on my work order "the bed must be fully up to hold the bed up". When I got home my wife as per instructions lifted the bed fully up in order to place some blankets in storage only to have it come down on her head. The dealer is now saying the gas spring are only to assist in lifting. I think they are covering up for the fact they should have replaced the gas springs.
I've had two Fleetwoods (9 years) and the current Winnebago (3 years) all with under bed storage. The gas struts do assist in lifting the bed but they definitely hold the bed up. I've never had to use any kind of prop when under the bed and we use it all the time for storage. That dealer is definitely jerking your leg, keep after him to replace them especially if still under warranty.
2004 Meridian 36G
We have replaced our OEM mattress with a memory foam matress which adds weight to the bed. Our gas springs will still hold the bed up. However, I still use a wooden stick to keep it open when we are in that space....just in case.
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.