HOW TO FIX GRASS BOX ON HAND MOWER

look up your model for the manual ------- https://www.mountfieldlawnmowers.co.uk/support

test to see if it is a bad switch. be sure there isn't any blockages keeping it in the alarm position. make sure all connections are clean and tight. physically with your hands take them apart and back together. loosen and sand grounds and put back together. a bad connection or grass build up can make a switch faulty.

Blades cut the grass and blow air like a fan. The clippings should flow along with the air out into the yard or into the bag. That only works if the bag acts like a filter and catches the clippings but lets the air out to be replaced by more air and more clippings until the bag is full of clippings.
The most likely problem is that your bag does not let the air out. Cutting wet grass will coat the inside like green paint. When dry, it's like the underside of your mower.
Check the inside. You might need to scrape and/or flush from the outside in. Can yours be turned inside out"? That would be the best case.
When clean and dry, it should work.
Didn't mention the easiest fix: to take out the hand-ful of clipping blocking the path to the bad: since you already checked that.

if you let grass grow to long will be to heavy to be picked up and go into bag

is there to much old grass built up under the mower?did you damages the blades

I have the exact same problem. I read on another site that the blowout hole in the back of the mower where the grass goes into the catcher must be cleared of any grass or dirt. I don't use the grass catcher and indeed the hole was full of dirt and grass. I cleared out what I could with my hands and a screwdriver, and magically somehow the cord retracted about a foot. Enough to start the mower with. It still doesn't retract all the way, but it was an improvement. I may have worn out the spring pulling and tugging on it trying to get it to retract, but ok for now.
Please share if you find a more permanent solution. Mower is barely a year old.

Hi, mine broke yesterday (Sovereign HG500B Grass Trimmer). I took the grass trimmer to Homebase but they've told me that this model has been discontinued and they don't sell spare parts for it. I believe it's still within the guarantee period so if I can find the reciept they'll organise some sort of replacement, but if I can find somewhere that sells a replacement spool cover I'd rather just buy that and replace it...so far no luck.

if it has a grass box,mow without it and then mow again with box or use a strimmer and then mow.