Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Automatic transaxle fluid (atf) inspection
Automatic Transaxle Fluid (ATF) Condition Inspection One way of determining whether the transaxle should be disassembled is by noting: If the ATF is muddy or varnished. If the ATF smells strange or unusual. ATF Condition Automatic Transaxle Fluid (ATF) Level Inspection Caution Th ...

Mazda 6 Service Manual: Master cylinder disassembly/assembly
Caution If the master cylinder body is damaged, replace the unit as a component. When securing the master cylinder in a vise, tighten only the flange of the master cylinder. 1. Disassemble in the order indicated in the table. 2. Assemble in the reverse order of disassembly. Stop ...