avalon 1126 pro 68T hashrate drop

Hello guys i have a problem with my miner and i would like to ask for your help.
My miner was working fine at 67-68T until past week. then the hashrate started to drop... Now it is at 61.2.
does anyone knows what is happening?
here is my log:

{'STATUS':[{'STATUS':'S','When':15008,'Code':11,'Msg':'Summary','Description':'cgminer 4.11.1'}],'SUMMARY':[{'Elapsed':15200,'MHS av':62062574.65,'MHS 30s':57003734.89,'MHS 1m':58811438.46,'MHS 5m':60802249.83,'MHS 15m':61174284.77,'Found Blocks':0,'Getworks':555,'Accepted':881,'Rejected':0,'Hardware Errors':731,'Utility':3.48,'Discarded':38661773,'Stale':0,'Get Failures':0,'Local Work':215986,'Remote Failures':0,'Network Blocks':28,'Total MH':943345789878.0000,'Work Utility':866984.26,'Difficulty Accepted':226394112.00000000,'Difficulty Rejected':0.00000000,'Difficulty Stale':0.00000000,'Best Share':244585934,'Device Hardware%':0.0003,'Device Rejected%':0.0000,'Pool Rejected%':0.0000,'Pool Stale%':0.0000,'Last getwork':0}
{'STATUS':[{'STATUS':'S','When':15008,'Code':70,'Msg':'CGMiner stats','Description':'cgminer 4.11.1'}],'STATS':[{'STATS':0,'ID':'AVA100','Elapsed':15201,'Calls':0,'Wait':0.000000,'Max':0.000000,'Min':99999999.000000,'MM ID0':'Ver[1126Pro-S-60-21072803_4ec6bb0_211fc46] DNA[02010000b749473c] MEMFREE[1297120.0] NETFAIL[0 0 0 0 0 0 0 0] SYSTEMSTATU[Work: In Work, Hash Board: 2 ] Elapsed[15201] BOOTBY[0x04.00000000] LW[15145861] MH[464 267] HW[731] DH[16.948%] Temp[34] TMax[141] TAvg[74] Fan1[6363] Fan2[6484] Fan3[6404] Fan4[6386] FanR[89%] Vo[329] PS[0 1221 1319 243 3217 1316 3540] PLL0[12064 777 482 597] PLL1[10059 980 885 1996] GHSspd[61281.98] DHspd[17.035%] GHSmm[74482.72] GHSavg[62057.40] WU[866931.87] Freq[668.85] Led[0] MGHS[29160.29 32897.11] MTmax[88 141] MTavg[74 74] TA[240] Core[A3201] PING[67] POWS[0] HASHS[0 0] POOLS[0] SoftOFF[0] ECHU[0 0] ECMM[0] SF0[660 680 700 720] SF1[660 680 700 720] PVT_T0[ 73 75 79 79 77 73 74 78 80 82 77 78 73 77 85 83 77 74 74 79 87 86 77 74 73 75 81 81 79 72 74 76 81 83 76 74 71 77 84 79 78 72 73 77 88 84 72 71 73 74 76 76 72 70 68 72 74 70 69 69 75 70 65 68 69 69 68 71 71 71 73 68 69 74 74 72 74 69 69 71 67 73 72 71 71 74 77 75 74 72 71 74 76 76 75 73 71 75 73 76 76 72 72 75 76 76 76 73 69 75 77 75 78 74 74 79 77 74 74 74] PVT_T1[ 75 76 78 77 77 73 74 74 77 76 74 74 72 73 79 79 76 74 73 75 78 79 78 74 72 79 77 81 75 74 74 76 141 81 78 74 74 74 76 83 76 73 71 73 82 76 74 75 70 71 79 74 72 72 67 74 72 84 81 70 67 69 68 71 70 67 69 71 72 73 74 71 71 78 75 77 73 73 71 74 74 71 74 71 74 77 75 74 72 74 70 74 75 74 74 71 71 74 73 72 70 71 69 76 76 74 73 74 71 74 78 77 73 74 72 77 74 68 73 73] PVT_V0[294 302 309 302 298 294 303 301 293 302 296 299 301 309 295 287 290 294 288 287 294 286 294 290 291 285 277 306 295 291 305 301 294 305 293 297 309 310 304 281 287 293 295 299 308 285 290 293 292 304 302 295 293 300 304 303 298 307 302 311 311 297 293 292 291 291 300 298 294 295 297 297 305 307 307 297 299 298 294 295 297 294 301 298 295 298 298 298 293 296 306 303 297 291 294 287 290 294 292 294 293 301 294 301 297 296 298 299 297 297 297 301 296 297 309 311 310 317 315 321] PVT_V1[293 297 307 312 305 303 307 305 307 289 286 291 301 309 297 298 303 295 281 281 285 291 296 308 300 298 301 306 308 297 301 293 337 311 299 301 298 306 303 283 283 287 284 287 285 291 306 303 296 295 314 298 295 295 299 294 293 301 317 323 322 310 300 300 305 302 312 310 319 298 304 305 294 293 295 287 290 292 290 290 288 292 293 293 311 317 340 293 307 305 294 292 294 291 292 295 291 290 287 288 292 294 294 304 307 305 299 302 318 313 304 302 305 295 316 306 302 305 309 301] MW[7578100 7578172] MW0[384 476 488 458 480 370 502 415 450 425 483 490 544 445 282 236 305 447 393 384 322 322 431 444 139 424 191 491 376 227 218 518 387 465 368 183 256 482 389 134 349 192 313 425 412 347 503 453 313 472 440 431 467 433 465 289 444 372 511 420 491 523 400 486 356 496 535 487 488 441 486 509 498 560 458 509 508 491 320 429 413 429 457 492 450 477 436 479 361 461 178 445 419 343 396 408 443 342 435 438 413 269 450 281 444 458 516 485 476 473 506 537 499 453 524 482 505 516 512 548] MW1[484 515 395 474 537 486 573 566 470 378 293 457 546 271 510 414 340 553 405 418 434 523 500 496 519 423 529 534 503 511 552 471 404 453 482 562 537 460 535 107 448 465 462 488 262 490 499 511 536 505 499 483 449 477 561 457 490 430 534 551 526 498 560 523 422 464 494 546 576 501 473 423 351 511 424 491 493 506 513 461 348 415 502 522 522 558 355 425 489 485 507 497 474 512 380 548 415 475 497 318 449 422 559 417 437 510 517 553 521 492 430 504 384 426 454 506 584 571 364 537] ASICCRC0[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] ASICCRC1[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] CRC[0 0] POW_I2C[OK] FACOPTS0[] FACOPTS1[] ATAOPTS0[--avalon10-freq 528:548:568:588 --avalon10-voltage-level 42 ] ATAOPTS1[--avalon10-freq 660:680:700:720 --avalon10-voltage-level 54 ] ADJ[1] COP[0 0 0] MPO[3200] MVL[87] ATABD0[660 680 700 720] ATABD1[660 680 700 720] WORKMODE[1]','MM Count':1,'Smart Speed':1,'Voltage Level Offset':0,'Nonce Mask':25}