The Great Big Lawnmower Thread

Pop the cover off the belt drive, there a few torx head screws holding it on. There you will see the belt drive/speed mechanism. The belt from the blade shaft pulley loops around the speed control jockey and idler pulley and from there to the drive shaft variable diameter pulley. Operating the speed lever should move the jockey against the belt, increasing the belt tension and squeezing open the drive shaft pulley, reducing its diameter and increasing speed. The mechanism can get packed with grass, and throw the belt off the jockey, leaving it stuck at low speed, and a slipping belt under load.

This mechanism is independent of the drive shaft gearbox internal clutch, operated by the drive grip handle lever bar and cable. This cable will have a spring at the end to the gearbox clutch lever, ( or at the handle end), and when properly adjusted, the clutch lever on the drive transmission should pull to its limit, with the spring taking up the last couple of cm of travel of the mower handle drive lever bar. While these little transmission clutches can fail, it's more than likely the drive belt slipping than the clutch.

When you get up from the seat with the engine idling and the blade disengaged, does it still cut the engine? It's manual transmission, so it should idle in neutral even if you dismount. If the blade engagement cuts it out it could be a jammed deck, you'd expect a belt squeal from this. Poor fuel mix would support idling but not running under load, and Inspect the gearbox neutral switch as @The Continental Op suggested. It might be stuck on or off, though it shouldn't affect blade engagement with a running engine. With those safety interlocks you can get funny results If any of them are disconnected. Check fur a central grounding point at the engine, sometimes there are a couple of ground wires to a spade connection grounding point which might pop off.

I assume you're not considering buying this from the UK, and at that price, which will surely be €100 more again you add additional Irish duty, VAT difference and delivery, plus you'll have no warranty to speak of, for what is essentially a cheap pattern 48cm mower. You can do much bigger and better for €700 and buy locally or in Ireland at least. This Stiga for starters is a 51cm robust 166cc model for €479 from the nationwide Tirlan agricultural group. What is your budget?

https://www.tirlanfarmlife.com/shop/product/Stiga-53S-Self-Drive-Mower/9143991

Husqvarna. Take your pick at that price.

McLoughlins distributors in Northern Cross business park Dublin 11 will supply parts over the trade counter, if you're near the M50, or you can ask in your nearest Topliine hardware store to order one in.

http://www.proplus.ie/contactus.html

https://maps.app.goo.gl/L9Wvuz9tbchzKAMXA

I'd suspect the deck belt tensioner, causing a loose belt. The belt itself may have disintegrated, and is slipping, but under full tension this would generally squeal and burn if there was full tension. The electric clutch could be faulty, it would not generally slip, just fail to engage. A engine oil leak onto the clutch could cause slipping Check the deck drive belt first, inspect for deterioration and damage, check that the belt is under tension from the tensioner jockey wheel, it may have ridden over it if a twig or other object got in under the cover.