You didn't say it its carpet on the walls or carpet on the floor. Assumed you meant on the floor.
I'd replace it. After 30 years it doesn't owe you anything and as a degreed microbiologist the thought of what may be growing in carpet that age makes me shudder. After that many years the accumulation of sloughed skin cells, hair, dust mites, mold spores, spilled food and who knows what else in a humid marine environment you likely have a science project that would make researchers swoon.

It's not hard. Go to any carpet store and buy a remnant. They have roll ends, etc. that they will sell you at reasonable price. I wouldn't be surprised if you can get a remnant for under $50, maybe a lot less. Use old carpet as a pattern to lay out and cut the new one if you can. You may want to consider having the edges bound or serged to give a nice finished edge and eliminate raveling but even that's not very expensive.