You have a Toro mower with a blade brake clutch system. One belt (short and heavy) drives the blade, while the other (longer and lighter) is for traction drive. You don't have to remove any engine mounting bolts to change either belt, but there is some disaasembly required. Unless you are a better the average garage mechanic, I would not attempt to do this service work. Depending on the year of the unit, you could easily get caught with a big repair bill. Just my opinion, I would replace both belts plus check the BBC idler pulley while everything is apart. This repair takes me between 45 minutes to one hour to do and I do about a dozen a season. Not a job I recommend you take on, and sorry I can find no manual to help you out.