Start with the bones: the frame

A floor loom is a frame held under tension, and everything else depends on that frame being square and sound. Before you look at anything clever, put both hands on the top and give it a gentle rock. A little flex in a large loom is normal, but a frame that shifts, clonks or moves as a whole has loose joints or a twist, and that will show up as uneven tension on every warp you ever put on it.

Sight along the uprights from the front and the side. Timber should be straight; a bow or twist in the side frames is very difficult to correct at home. Check every joint for movement, and inspect bolts and wing nuts — many older looms have been over-tightened by decades of well-meaning owners, splitting the timber around the fixings. Run your fingers along the bottom edges and around the back, where damp and woodworm show first. Fine, fresh sawdust beneath the loom means active woodworm; small holes alone may be historic, but if you are unsure, walk away. Steel and aluminium frames are less prone to movement, but check for heavy rust, flaking paint and seized bolts, especially on the treadle and beam fixings.

Shafts, heddles and the harness

Count the shafts carefully, because they largely determine what you can weave. Four shafts will keep you busy for years; eight opens up more complex patterns; sixteen is a serious commitment in both space and threading time. Then look at what is hanging on them.

• Heddles: metal heddles should be straight, clean and free-moving on the bars. Rust is common on looms stored in sheds and garages, and it will abrade your warp. Count how many are missing — replacing heddles by the hundred adds up quickly.
• Heddle bars and cords: check for bent bars, perished cord and stretched or snapped ties. Texsolv and cord are cheap to replace; bent metal bars are not.
• Lifting mechanism: whether jack, countermarch or dobby, raise and lower each shaft by hand. They should move freely and sit level. Stiffness usually means worn or misaligned guides rather than anything terminal, but a shaft that will not sit level will give you a permanently sloppy shed.

Look at the lamms and treadles too. Check the tie-up cords, metal hooks and treadle rubbers. Missing hooks and perished cord are a weekend's work; cracked or snapped treadles are a bigger job.

The reed and the beater

The reed is the comb that determines your sett, and it takes most of the wear. Hold it up to a window or a torch. The dents — the slots between the wires — should be evenly spaced and perfectly straight, with no kinks, rust or gaps where a wire has been pushed out of line. Reeds are usually marked in dents per inch, though you will also find metric reeds; make sure you know which you have, as it affects your calculations for every project.

Now swing the beater. It should move freely through its arc without binding, and the shuttle race should be smooth, with no splits or splinters that will catch a shuttle. Check that the reed sits squarely in its groove and that the beater arms are not cracked at the pivot. A replacement reed is a modest expense, but a warped or broken beater is often more trouble than the loom is worth.

The brake and tension system

This is where bargains can turn sour, and it deserves more than a glance. Most floor looms use either a friction brake — a band or strap running against a drum — or a ratchet and pawl. Whichever it is, it must hold the warp firmly under tension while you weave.

• Friction brakes: look at the brake band for glazing, wear or fraying, and check the drum surface for polished, slippery patches. Test it by winding on tension and pushing firmly against the beam.
• Ratchet and pawl: the teeth should be crisp and square, not rounded off or hooked. Make sure the pawl drops fully into every tooth and does not jump out under load.
• Springs and levers: a weak or missing spring is a common cause of a loom that slowly loses tension as you weave.

Also check the warp beam and cloth beam ratchets, and any sectional beam pegs. Missing pegs are easy to replace; a worn ratchet wheel can be genuinely hard to source.

Beams, aprons and the small parts

Peer at the aprons and cords on both beams. Perished cord, frayed apron tape and rusted hooks are all straightforward to renew, and knowing the cost helps your negotiation. The same goes for the raddle, lease sticks, threading and heddle hooks, shuttles and bobbins. A loom that comes with a spare reed, a warping board or frame, and a decent bench is worth noticeably more than a bare frame, and it will get you weaving sooner.

Before you commit

Take a tape measure, a torch, a small screwdriver and a notebook. Measure the footprint and the height, and check the loom will fit through your doorways, up your stairs and under your ceiling — a dismantled floor loom is heavy and awkward, so ask how it comes apart and whether it is currently assembled and working.

Ask to treadle through a sequence and watch the shafts rise and fall evenly. Sit at the bench and check the weaving height suits you, because a loom you do not enjoy sitting at will gather dust. Finally, know when to walk away: severe woodworm, a badly twisted frame, a seized or incomplete brake assembly, or a loom missing half its shafts and heddles. A sound, complete older loom with a little cosmetic wear will usually serve you far better than a cheap one with hidden faults.