The first thing to check when diagnosing a transmission problem is the fluid level and condition. Transmission operation relies on proper lubrication and hydraulic pressure, and a low or contaminated fluid level can cause slipping, hard or delayed shifts, or even a failure to engage gears. This check is quick and can reveal leaks or fluid degradation that are common culprits, letting you rule out or address a simple cause before diving into more complex electrical or mechanical issues. To do it right, ensure the vehicle is level, the engine is running, and the transmission is warmed up, then check the dipstick for the correct level. Look at the fluid’s color and smell: fluid that’s dark, burnt, or has grit or metal particles points to contamination or wear and should be serviced. If the level is low, locate and repair leaks and refill with the correct fluid. If the fluid looks or smells off, follow the manufacturer’s service procedure (which may involve a flush or a full replacement). Only after confirming the fluid is correct and clean should you investigate other potential causes like gear selector alignment, electrical wiring, or mounting, since those issues are less likely to be the root cause once fluid condition is good.