I have a Bosch 1617 that the variable speed is not working properly. The router sat on the shelf for quite a while . It worked just fine when last used. The on off switch works ok but the speed wanders up and down. I am not certain but I dont think it is reaching max speed at all. The speed will change when I adjust it but wont stay constant. Ant thoughts on this beyond getting a new switch. I dont want to start changing parts till I know what is wrong Thanks.