when driving there is a hard knocking sound every time a transmission shifts gears
sounds as if your transmission is having either an issue with stuck/jammed bands,a clogged filter,or low fluid.the fluid is easiest to check, (hot engine,idling,read what the dipstick tells you,if low add correct grade of automatic transmission fluid,which will be in owners manual.you can also add some lucas trans fix at this time as well) if the level is ok,you may just have a clogged/dirty filter,which means its time for a full flush,choose a actual mechanic shop that will physically drop the pan and replace the filter,back flushing doesn't always fix the problem.the 3rd scenario will again need a mechanic shop,and they will possibly have to partially disassemble the transmission.but it wont have to be removed from the vehicle.they will check the operation of the bands/and clutches for ease of movement and check tightness and wear on the bands.they should also at this time spray a cleaner into the transmission ( brake cleaner usually,since the bands are just brake pads in essence,and the cleaner wont damage them ) and that will remove and gum and varnish that is interfering with the transmission.at this time they can also check the valve body for clogs as well.( some shops will perform this as part of a normal service to the transmission,during a flush,and will tell you if there is a problem in need of more attention or if everything is ok. you'll have to use your best judgement on a reputable shop
