Hard shift from 1st to 2nd on 1991 Volvo 940

On level ground and at low RPM it will shift smoothly but with normal acceleration it is a hard shift. All other shifts OK . Any ideas ?

Asked by for the 1991 Volvo 940
The kick down cable is a big problem with these, but it can be something else too. It's hard to say without driving the vehicle. Start by having the cable checked, as well as the transmission fluid level and condition.
Here are some places if you need one: