The bands may be weak, it may be low on fluid.
One of the most common causes of gears in a Mercedes Benz A class 160 automatic gearbox to slip and not shift up to higher gears is a bad transmission. If the transmission is failing, or not working properly, you won't get the gears to shift up.
Means that the transmission is delaying going into the next gear.
Transmission temp sensor can cause a slip or high rpm before shifting to next gear.
because the transmission is going out, it need rebuilt or replaced
check your transmission fluid, if it is low it will slip
does the speedometer effect the transmission
Yes. From low fluid, plugged filter, or an internal failure.
A 1994 Mazda Miata's automatic transmission may slip in 4th gear if the bands are heavily worn. When the bands become worn, they are unable to grip properly and cause slippage.
I'll assume you mean an automatic. If so, there are friction plates inside the transmission that get worn out and just like old sand paper gets smooth and doesn't do it's job very well, the friction plates get smooth and don't grip anymore, causing the transmission to slip. In the possible case it is a standard transmission, it isn't the transmission, it's the clutch slipping.
overheating of the fluid. This causes the transmission to slip. Slipping causes damage as friction material wears out quickly and even more overheating. This eventually causes failure.
check the fluid levels. that's the only thing I can think of.
Low transmission fluid will cause this and also weak bands inside the transmission can cause this.