I took my moped to the shop for the first time after buying it used, its a 94. 10 yrs old. bout 3000 miles. but anyways i took it to the shop in hope of bringing it up to speed and fix various things, one thing that hasnt changed it my shifting. It will not shift into second on uphills and it is very slow shifting on regular streets. it makes a whinning noise when it takes off. and say im going down the street i can feel the moped and i know when to ease off the gas to help it shift into second, if i didnt do this ease off gas thing, it probably wouldnt shift. any ideas?