Quote from: Mick on October 26, 2026, 06:47:58 PMHi Tim.

I'm assuming the control arm on the gearbox is moving freely on the gearbox, and the return spring is pushing it all the way back. That control arm shaft has been known to seize up or go very stiff.

That's really the only thing that would cause it, unless there's a problem inside the box. Has it got the correct oil in it, and the correct amount?  Also make sure the control arm hasn't got excessive play on the shaft or it might be hitting its stop tab before releasing.

Yes mick, filled with Honda HST fluid and control arm is moving freely. I think it's something inside the box tbh. Thanks as always!

Hi Tim.

I'm assuming the control arm on the gearbox is moving freely on the gearbox, and the return spring is pushing it all the way back. That control arm shaft has been known to seize up or go very stiff.

That's really the only thing that would cause it, unless there's a problem inside the box. Has it got the correct oil in it, and the correct amount?  Also make sure the control arm hasn't got excessive play on the shaft or it might be hitting its stop tab before releasing.

Hello Mick and all,
Weird one for you. Belt driven hydrostatic box on a HRD536 HX....wont roll backwards. The gears ⚙️ on each wheel are correctly orientated. shaft won't turn backwards unless the mower is running and the belt is turning. Dismantled off the mower and still shaft won't reverse direction. checked hydrostatic fluid level which is good. No air in system. Any thoughts? Thanks, Tim

Thanks for the reply Mick. Terry

As far as I'm aware there's a 6.3A fuse on the circuit board.  Number 4 in this parts diagram. https://www.diyspareparts.com/parts/mountfield/diagrams/96bcd53a-924e-4463-a601/1b74fe48-08fe-4bd3-8596

It is possible that the electrics are different on your machine, they can be a right pain.

I have a Mountfield 1228H and cannot get any sign of electric power. I changed the carburettor after lifting the body up from the chassis to gain access. When I dropped the body back down afterwards I had no power at the ignition. All the micro switches are disabled apart from the the blade drive, so not sure what is the problem. Are there any fuses, if so where can I find them. I have also fitted a brand new battery. Any help would be much appreciated. Terry

Second update, mostly for the next person who searches for kikuyu and clogging.

Cut it again this morning, three days after the last one, and the silicone is still doing its job. There was a thin crust by the chute again but nothing like the old packed layer, and I didn't have to stop once. So two coats seem to last at least two cuts, I'll keep an eye on when it wears off.

The mowing day thing turned out to matter more than I thought. Weekends here are planned around the football, I'm a Chippa United supporter and I check the kick-off times on https://chippaunited-fc.co.za/ before deciding when the lawn gets done, so on match days it used to be a rushed cut in the late afternoon on wet grass. Now I do it in the morning whatever the fixture is, and the dry kikuyu goes through the deck far better.

Still on the old blade. When it goes I'll fit the high-lift one and say how the 3.5 hp handles it. If anyone has run a high-lift blade on one of these small side-valve Briggs engines, I'd like to hear whether it struggled.

Quick update in case anyone else with kikuyu finds this thread.

I did the cheap things first. Scraped the deck back to bare metal, wire brushed it, and gave the underside two coats of silicone spray, letting the first one dry for an hour. Cutting on Saturday it went the whole lawn with only a thin layer stuck near the chute, which is a lot better than before. Not sure how long the spray lasts, I'll see after a few more cuts.

The other thing that made a difference was timing. I used to mow late afternoon after the sprinkler, and the clippings were basically paste. Mowing before lunch when the grass is dry, with the wheels one notch higher, the engine hardly bogged at all.

I haven't changed the blade yet. A high-lift one for this model is about R350 at the local spares shop, so I'll try it once the current blade needs replacing and report back on whether the 3.5 hp copes with it.

Hi all, first post. I'm in Gqeberha in South Africa, so some of what I describe might be a bit different from what you get in the UK, but the machines are mostly the same.

I've got an old 18 inch rotary with a Briggs & Stratton 3.5 hp side-valve, no brand name left on the deck, bought second hand years ago. The lawn is kikuyu, which if you haven't met it is a thick runner grass that grows like mad in summer. If I leave it more than ten days the mower bogs down and the underside of the deck packs solid with wet clippings, then it starts throwing them out in clumps and leaving stripes.

Things I've tried: sharpened and balanced the blade, cleaned the air filter, cutting higher and doing two passes. It helps, but after about half the lawn I'm on my back scraping the deck again.

Is it worth fitting a mulching blade or a higher-lift blade on an engine this size, or will that just make it bog down more? And does anybody put anything on the underside of the deck to stop the build-up? I've read about silicone spray and also about people painting them, not sure what actually works.

Hit a thick branch hiding in the weeds near the pasture fence and completely cracked one of my deck spindles. The local dealership wants an absolute fortune just for the replacement spindle housing and a couple of bolts. I'm going to shop around online and buy some aftermarket john deere lawn mower parts instead to keep this repair affordable. For those of you maintaining older machinery on a tight budget, do these third-party replacement parts hold up okay against rock impacts, or am I going to end up replacing it again in two months?