Occasionally, you have to push hard (and wiggle) the connector to get it in to fully seat into the radio.  This is to keep a water resistant seal between the connector and the radio case to keep water from getting into the connector on the radio.  If the connector isn't fully seated, you are only able to hear and not transmit. Motorola 2 prong M1/ GP300 -  2 Prong Plug with 2.5mm and 3.5mm plugs with 8mm spacing:

XTN Series: XTN446, XTN500, XTN600

XTN XV Series: XV1100, XV2100, XV2600, XV4100

XTN XU Series: XU1100, XU2100, XU2600, XU4100

XTN AX Series: AXV5100, AXU4100

CLS Series: CLS1110, CLS1413, CLS1450, CLS1450C, CLS1450CB

Motorola Spirit Series: SV10, SV11, SV11D, SV21, SV12, SV22, SV22C, SU210, SU22, SU22C, SU220 VHF / UHF Spirit, Spirit Pro, Spirit Pro+, Spirit HP 10

Spirit MU Series: MU11, MU11C, MU11CV, MU12, MU12C, MU12CV, MU21C, MU21CV, MU22CVS, MU24CV, MU24CVS, MU24CVST

Spirit MV Series: MV11, MV11C, MV11CV, MV12, MV12CV, MV21C, MV21CV, MV22CV, MV24CVS

CP Series: CP88, CP040. CP100, CP110, CP125, CP150, CP200, CP250, CP300

GP Series: GP2000 , GP2100, GP300, GP308, GP68, GP88, GP88S

SP Series: SP10, SP21, SP50+, SP50

CT Series: CT150, CT250, CT450, CT450LS

PRO Series: PRO1150, PRO2150, PRO3150

P Series: P040, P080, P1225, P1225LS

DTR Series: DTR410, DTR550, DTR610, DTR650

Other Series: GTI, GTX, LTS2000, VL130, PMR446, ECP100, Mag One BPR400, EP450, AU1200, AV1200

RDX Series: RDV-5100, RDV2020, RDU2020, RDU2080DD, RDU4100, RDU4160D, RDV2080D, RDV5100

FDC: FD-150A, FD-450A, FD-160A, FD-460A

Blackbox Series: Blackbox-V, Blackbox-U (M1 Connector)