Short wave is more sensitive to small variations of tuner capacity. At higher frequencies, short wave, it takes less capacity change to tune a range of frequencies. Even temperature change can cause noticeable drift. Some receivers have a band spread dial which helps tuning.
Make sure hardware is tight. Try to take sideways movement out of your dial.
Norm
:just bought a nice delco am/shortwave model r 1177. Question is .....Is shortwave tuning really sensative...I.E. sneeze on the tuning knob, and you just lost the station. the set seems to get quite a few stations well, just difficult to tune the dial just right. sometimes you have to tune to find a certain station several times to get it. Wiggling the knob sideways just slightly has an affect on tuning...maybe due to dial string tension. sometimes wiggling can make the station come in better