Have you tried using E5 in it?

My McCulloch, 21" petrol power drive rotary mower - starts usually with 3/4 good pulls at the start of the mowing season - fresh E5 petrol every spring. Autumn 1/2 gallon or so goes in the car

For the rest of the summer rarely fails to start on first pull.

Never had it serviced, oil changed by me every 2 years or so.

It was £220 to buy in 2012 - servicing the local outlet wants £70+ - bangernomics although it was bought new. If it last 4 years it owes me nothing.

Although still fine at cutting the grass the body is rusting. Negotiating with SWMBO about a new one cost is around £350 - Costco usually take £100 or so off about now - that would bring it down to under £250 - we have authority to buy anything under £250 without clearing it with one another.

It's not a matter of counting the pennies nowadays - it stretches back 54+ years to when we had mortgage and then 3 kids that seemed to appear from nowhere.

My dad always swore by Hayter for small mowers, so some years ago i bought one, not only did it need regular cleaning of the carb jet to ensure starting and running the thing would clog up numerous times each cut unless the grass was absolutely bone dry, spent £110 on a full service only for the same starting issues by autumn of the same year.

Enough, so already having some DW batteries splashed out on a Dewalt mower, its a bit of beast a bit like an offroader of rotary mowers but sadly lacking self drive, however it laughs at wet grass and just does the job no matter what, not cheap but very well built, probably worth the extra for self drive unless fit enough for push power.

I bought an Aldi electric mower when it was on sale 8 years ago. Still going strong cuts wet grass but need to clean chute into basket but easy done. £35.00.

Paid for itself many times over.

I found electric lawn mowers are better over petrol or battery because

1. uninterrupted power supply for long time (good for large lawns)
2. almost no maintenance (except change of blade every ~3 years)
3. reasonably priced

I use with an extended cord to cover the end of the garden. Just need to be careful that I don't run over the cable :-)