Transmission problems can be expressed in terms of shifting at random, not engaging at all, or in failing to downshift during hard acceleration. In regards to fluctuating shifts the first step is to check the fluid level in the transmission along with the type of fluid needed. Check the condition of the fluid; if it looks dirty, smelly or if it has some burning smell, replace the fluid and the filter. Check the condition of the transmission filter and ensure that it is properly fitted while gauging the fitness of the gaskets and fittings for some looseness or leakage. Also check shift and throttle linkages for breaks or play. Lack of engagement of this transmission calls for checking of shift linkage for wear and ill-proportioned adjustment as well as confirmation of adequate fluid level. Even if the linkage is installed correctly and the fluid levels are adequate, more internal damage may be done requiring a disassembly of the unit. For downshift problems during heavy acceleration, look for faulty sensors or control units in computerised transmissions, and check the settings of kick-down linkages and vacuum servos in other types. Electrical connectors should be secure and cleaned; however, cleaning agents for electrical contacts should be appropriate.