I notice you’re from the Tyne Valley and I’m from Sunderland so here’s a joke in local dialect: I recently went to the Doctors who is a Geordie. I said Dr I have knee pain when I’m cycling. He said if you have nee pain, what’s your problem?
Update from my post of 4 years ago. To contribute to my good health, I now avoid all processed food wherever possible. Also, I’m on a meat free diet, no alcohol, sugars or smoking. I’m 86 now and still do a regular 17 mile cycle route daily when weather permits.
There is a set of numbers stamped on the down tube at the base. The first 2 numbers after the letters is the wheel size followed by possibly FX and 2 numbers which was the year of manufacture
The problem to me judging from your photos of the magnet is simple. Turn the bike upside down like has been suggested and give the magnets, ring and sensor a jolly good clean. Free, no cost, and simple to do as a first step.
Whoa! Not so fast. This cold weather reduces battery miles by up to half, same as an electric car. I myself am down to 30 miles but in the Summer it’s 50 miles easily.
wait a couple of months before you write the battery off or get more miles.
Found it, mine is a Ridge brand with a shoulder strap, but seems to be only 75 x 67 x 43. Have a search on eBay I would think there should be different sizes.