Would it be possible try the welder plugged into the house sockets, even on a short extension lead to rule out voltage drop?
You're asking a lot from a long length of 1.5mm cable
If this is a flapper valve, I don't recommend using a lurpak spreadable lid as a long term fix. The damp proof membrane replacement seems to be more durable
Is there a small water reservoir with a pump and float switch at the rear that pumps water to the removable drawer?
If this is full the machine won't start, I've had to replace a perished rubber impeller on a pump which wasn't draining this reservoir
I initially thought the same as you, welding supplies direct seems to be the only place that describes it as a 17 sized torch but CK call it a reduced size 26
Open up the battery pack and look for the number printed on the cells to Google, you should be able to find the specifications for them.
Ive removed the cells from a few makita 18v 3ah batteries and although all different types, they were all 10a discharge cells
Is this the welder from another post where you measured the primary windings and found 0.5ohms?
Itll be drawing about 500 amps.
The insulation on the windings is knackered
https://ec.europa.eu/taxation_customs/business/vat/modernising-vat-cross-border-ecommerce_en
The same rules are going to apply to all EU countries from July this year, the implementation was delayed for 6 months due to covid. Puppy dog is not the cause.