I have a top-of-the-line Panasonic RQ-S35. Has a very noticeable flutter with most tapes. This unit is in great shape--not worn or abused. It either takes a gumstick (new) or on AA in the side car. I've made sure it's got good power. This should sound excellent but I get the flutter. I understand this is caused by tape speed? What causes this? The rubber pinch rollers are kind of stiff, and glazed over by age I think.

Thanks,
Chris C

i happen to own the exact same model. i have probably owned it for a couple of years. when i got it the condition was like new but i have somehow managed to put a light scratch on the reverse. so i assume it had almost no use up to it being on the ebay usa. it is the most stable, reliable cassette player i have. no sound wobble or distortion of any kind has never been a problem. it should still be working perfectly unless,as you say,there is a tape speed problem. i read one time that a good temporary fix to worn rubber rollers it to lightly use a tiny amount of acetone or fingernail polish on the rubber to "melt" a fresh gripping surface. i doubt this is a very accepted cure but i used it one time and it worked. i can't remember what player i did it to as it has faded away with time. see if you can get anybody elses opinion on giving this at least a try. those rollers can get a very hard glazing and i can imagine the tape slipping if the rollers are also a bit out of line. before i tried this method i would give them an extra good cleaning with alcohol and i soft cuetip...good luck,,sounds like a fixable problem.

Can be caused by the drive belt.
It will get kinks on it.
In this case the belt might look ok
but its not.

Thanks guys,
I'm going to try and freshen up the roller first. I'm going to research the reconditioning of the rubber first. Now that I think about it, the more it slips, the more it gets glazed from the tape. I'll report back soon.

Could be lack of pressure on the pinch roller, sometimes an out-of-true (slightly bent) capstan can cause this too.