Minolta x-300

I have my father's Minolta X-300. It all seems to work, I fitted new batteries, but there is a delay in the shutter speed.
When you look in the viewfinder, you see the speeds on the right and depending on the light/aperture/etc. 2 red lights light up the proper speed, but there is a flashing red light at 1 or 1/2 all the time,and the shutter works at that speed.
Could anyone tell me what I have done wrong, my Dad used it some time ago and it was alright, so I have got it wrong. Thank you. John