What's wrong with my trimmer? Line won't advance

Black & Decker ST4500. A few years old.
New B&D spool? No change. Yes it is the right spool.
New spring? No change.
The spool moves freely in and out but the line does not advance. Is it a fixable problem or should I buy a new one?

Did you wrap the line around the spool in the correct direction?

The spool comes with the bump cap so it is impossible to not put it in the right way.

I take it that Saint_Cad purchased a factory spool that was already wound so couldn’t have been wound incorrectly.

I’ve wound my own and found they often have this problem whereas the ones where they are ‘pre-wound’ work fine. I’ve concluded that I wind them too tightly or with too much line or not in a nice pattern. So I’ll either buy them prewound or put less line on the ones I do.

I assume this means this is the kind of trimmer that you bump on the ground to advance it? If you hold the line with one hand and press the bump cap with the other, does the line advance freely?

I have a trimmer that feeds automatically, I don’t have to bump it. But I had trouble with mine this weekend where it wasn’t advancing. After taking the spool assembly apart, I found that the line had gotten caught between the spool and the housing last time I put it back together. I had to put it back together being careful not to pinch the line somewhere as I clicked the spool back into place.

Nope and I have checked that the line is not caught. I suspect the spring but I’m not exactly sure what’s wrong with it.

Please tolerate this question:

Are you sure the motor is turning the spool, i.e., if you take the spool out and press the trigger, can you see the motor shaft spinning? (Please wear safety glasses.)

Yes because it is wacking weeds. Just not advancing.

I have a Black & Decker weed whacker, not the same model as yours. If you can hang on until tomorrow morning, I’ll take a look at it and see if it’s similar to yours and we can compare notes and maybe find an answer.

I’m back. My B&D WW is auto feed; I Googled the manual for your model and it doesn’t seem to be much help. Are we going to let a WW get the best of us? Hell, no! I had a B&D bump feed 20+ years ago, let me think on it awhile.

Try this YouTube clip, it says something I hadn’t thought of – the replacement spool might be out of spec. If you have the other spool (the one that was working), feed some line onto it and see if it advances, if it does, the replacement spool is a dog. This would not surprise me at all.

So I got some off-brand spools for cheap off Amazon and they were out of spec. I went back to the B&D brand and they fit perfectly. However, I am using the spring from that off-brand so that’s why I think it’s the spring. It just doesn’t seem to sit right.

I think you’ve solved your problem, there isn’t a whole lot more it could be. Any chance you still have the old spring?

Replacement parts being not-quite-right is always – ALWAYS – the last thing that crosses my mind, I don’t know why.

I don’t know about your model trimmer, but there are kits that are sold seperately for alot of brands for people who want to get rid of the plastic strings that wrap around a spool, and all of their complications that are listed above.

These attachments that replace the spool are spinning metal cutters of various sizes and designs depending on the type of work you need to do with your trimmer.

There are cheaper hard plastic versions of these cutters as well.

The advantages are is that they do not have to be replaced as often as you have to replace spools.

And you don’t have any issues like you do sometimes when you have to push down on the trimmer to advance the string, and it doesn’t work properly.

And, I think these cutter kits just do a better job than the string and spool.

The kits are sharper, and the blades have a wider range, so the job doesn’t take as long.

I do find it strange that none of the familiar brand names of trimmers actually come with the kit attached.

You have to buy them seperately.

There clearly seems to be a demand for them.